
Ciass^QlL33 



Book 



-^.^ii 



Copyright N°, 



COPYRIGHT DEPOSnV 



Text Book of Chemistry 



For the Use of Students 

of the 

Cincinnati Veterinary College 

By 

J. HENRY SCHROEDER, Ph. G., M. D. 

Professor of Chemistry in the College 



fuBRARY of GONiiUSsj 
I Two Copies Rgctsived 

DEC 20 i90J 

\ Cof),yr!a;ftt tniry 
feOPY B. 



COPYRIGHT, 1907 
By J. HENRY SCHROEDER, Ph. G., M. D. 



PREFACE 

The preface is chiefly required to state the limits 
of Tisefulness which have been outlined for this 
volume. 

It shall serve as a text for the lectures in chemis- 
try in the Cincinnati Veterinary College, and not 
take the place of the lectures. Moreover it is not a 
book of reference. 

The aim in preparing the manuscript has been 
to adhere to the greatest simplicity in stating the 
subject; to develop in logical order the laws of 
chemistry and their application. It is required that 
the student shall know and understand the subject 
within the limits herein outlined. 

That the book may fulfill its mission within its 
own limits, is the wish of 

THE AIJTHOE. 
Cincinnati, 
]^ovember, 1907. 



TABLE OF CONTENTS 



Page. 

Matter, Elements, Molecule, Atoms 5 

Force, Cohesion, Cliemical Affinity 6 

States of Matter 6 

Specific Gravity 7 

Heat, Latent Heat 7 

Electricity 10 

Elements, Symbols, Valence 12 

Cliemical Compounds, Radicals 14, 15 

Atomic and Molecular Weights 16 

Acids, Bases and Salts 17 

Solution, Ionization 20 

Electric Decomposition 21 

Deliquescence, Efflorescence 22 

Dialysis, Osmosis 23 

Cliemical Formulae, Reactions 23 

Inorganic Chemistry 25-43 

Chemical Incompatibility 44 

Chemical Analysis 45-48 

Organic Chemistry 49 

Open Chain Series 50, 53 

Closed Chain Series 52, 62 

Amines and Amides 59 

Carbohydrates 60 

Derivatives of Vegetable Drugs 66 

Fermentation 68 

Chemistry of Proteids 69 

Chemistry of Foods and Digestion 72 

Chemistry of Urine 75 

Chemistry of Milk 79 

Chemistry of Meat and Food Products 85 



PART I 



THE THEORY OF 
CHEMISTRY. 



MatteKj Elements, Molecule, Atoms, Mass, 
Volume. 

The study of chemistry is the study of the con- 
struction of matter, and of the laws governing the 
changes therein. Matter is anything that occupies 
space, and can be apprehended by the aid of our 
senses. The agency that brings about chemical 
changes is called force. A chemical change in mat- 
ter destroys its identity, and a physical change 
merely its outward form. 

Matter is divided into simple and compound mat- 
ter. The former consists of one element only; the 
latter of a combination of elements. An element 
is the simplest substance known. Some seventy 
elements have been isolated, but only a limited num- 
ber are of practical importance for our purpose. 
All material things are, therefore, made up of a 
combination of these elements, or of single elements. 

The quantity of matter forming a substance is 
called its mass, expressed in units of weight. The 



— 6 — 

amount of space it occupies is called its volume. 
The relationship between a given weight of the 
mass and its volume is proportional to the density of 
the mass. 

A Molecule is the finest and smallest particle of 
a mass of matter that can exist in a free state. It 
forms the limit of physical subdivision. By chemi- 
cal means, however, a molecule may again be sub- 
divided into two or more smaller particles, called 
Atoms. An atom is, therefore, the smallest par- 
ticle of matter that can enter into chemical combi- 
nation (to form the molecule). 

It is a fundamental law in chemistry, that matter 
can not be created or destroyed. 



FoKCE, Cohesion, Mass, Chemical Aefinity. 
States of Matter. 

Force applied to matter is the direct cause of all 
physical and chemical changes. Without force 
matter would not change its state or position, it 
would be in a state of inertia. It is a force of grav- 
itation, cohesion, that holds the molecules together 
to form the mass. Cohesion is, therefore, a mole- 
cular force ; the difference between molecule and 
mass is one of form only. The atoms are chemically 
combined by a chemical force, called chemical af- 
finity, inherent in atoms and elements, that causes 
atoms and elements to combine with each other. 

The degree of compactness with which molecules 
are arranged within the mass, gives rise to three 
states of matter called Solid, Liquid, and Gas. The 
cohesion is greatest in the solid and least in the gas. 



— 7 — 

Specific Gravity. 

Matter possesses weight and volume for a given 
mass. The comparative weight of different bodies 
of equal bulk is called their ' 'specific gravity." It 
is not actual, but the ratio of relative, weight. Thus 
a given bulk of water weighs lib., the same bulk 
or volume of glycerine weighs IJlb. The glycerine 
is 1.25 times heavier than water: 1.25 is its specific 
gravity. Water is the accepted standard — its specific 
gravity is 1. 

Weights and Measukes of Mass. 

The imits of mass are expressed in various sys- 
tems of weight. The old (American) system of 
weight consists of the pound unit, having 16 
ounces of 437.5 grains each. In the same system 
the unit of volume is the pint, having 16 fluid 
ounces. The modern and simpler system, however, 
is the metric system of weights and measures. The 
unit is thQ gram, which is the weight of 1 cubic cen- 
timeter of water at 15°C. 1000 grams forms 1 
kilogram, and 1000 cubic centimeters form 1 liter. 

Heat, and its Action upon Matter. 
Latent Heat. 

The force initiating all changes in matter is heat. 
The original source of heat is the sun. It sets in 
motion molecules and atoms, producing physical 
and chemical changes. 

Molecular motion is produced by, and is accom- 
panied by the production of, heat. Greater mole- 
cular vibration exhibits increased heat, and finally 



it is accompanied by light (and electricity in certain 
bodies). 

Aside from the original source, the sun, heat may 
be produced through friction and also through chem- 
ical changes (example, burning of a candle). 

Changes produced hy heat. 

Heat acting upon matter produces increase in 
volume, by counteracting molecular attraction. 
Acted upon by heat, solid bodies melt, or fuse, at 
a temperature called the melting pointy which is con- 
stant for the same substance. When a substance 
begins to melt, the temperature does not rise 
further, until the melting is complete, no matter 
how much more or greater heat is applied. This 
heat which during the process melting is absorbed, 
is stored up within the melting substance, and is 
called latent heat, because it is capable of doing 
work. It is given off in the same amount, if the 
melted substance solidifies again. 

Heat applied to a liquid causes it to boil, at a 
temperature called the "boiling point.'''' It is con- 
stant for the same fluid under the same condition. 
Heat is rendered latent in the change from a fluid 
to the gaseous state. (The solidifying point of a 
liquid substance is likewise constant.) 

Crystalline and Colloid Matter. 

Substances passing from a liquid to the solid state 
may assume certain forms of definite outlines and 
angles, called crystalline forms. Substances in- 
capable of assuming such forms are called colloids, 
or 'Vax like." "'Kock Candy" is a good illustration 
of a crystalline formation. 



Evaporation and Distillation. 

Even at ordinary temperature water or many 
other fluids slowly vaporize, and more rapidly at a 
higher temperature. The process of vaporizing a 
liquid is called evaporation. It is proportional to 
the amount of heat applied and to the surface ex- 
posed to the air. 

If the vapors are collected and cooled by abstract- 
ing the latent heat through a colder medium, the 
vapors enter, or change, into the liquid state. The 
process of vaporizing and condensing a liquid is 
called distillation, and the apparatus a still. Liquids 
having a low boiling point may be rapidly vaporized 
at a correspondingly low temperature. The more 
rapid the vaporization the greater the cold produced 
in the surrounding medium through the abstraction 
of heat. When readily soluble substances are dis- 
solved in water, the temperature of the surrounding 
medium likewise falls, because of the heat absorbed 
by the dissolving substance. Upon this principle 
freezing mixtures are prepared. When, however, 
a chemical change is accompanying the process of 
solution, the temperature rises in the dissolving 
medium. 

Measurements of Heat, Thermometers, Calories. 

The amount of heat produced is measured by the 
thermometer, which registers the expansion of a 
column of mercury according to a fixed scale. Upon 
each thermometric scale, there are marked two fixed 
points, the freezing point and the boiling point of 
water. The Centigrade thermometer fixes the boil- 
ing point of water as 100°, and the freezing point 
as 0°. This temperature is designated upon the 



— 10 — 

Fahrenheit thermometer as follows : Freezing point 
32°, boiling p. 212° ; upon the Reaumur scale : 
Freezing point 0°, boiling point 80°. The Celsius 
scale is the same as the Centigrade scale. 

The amount of heat that may be generated during 
the complete combustion (burning) of a substance 
of given weight, is called its Caloric value, the units 
Calories. 

Chemical Effects of Heat and Electricity. 

It has been stated that heat separates the mole- 
cules in the mass; it increases molecular motion. 
When the molecule is one of compound matter, it 
may be decomposed into its elements, if the degree 
of heat applied is sufficiently high. Or, if it is a 
molecule of simple matter it may be decomposed 
into its atoms, which, in turn, may produce other, 
and different, combinations at this temperature, ac- 
cording to the medium of matter which they meet. 
Heat may, therefore, induce chemical decomposi- 
tion and produce chemical combinations. A low de- 
gree of heat merely favors any chemical change be- 
tween different substances, by increasing the surface 
contact of the molecules. 

Electricity. 

It has long been known that the electric current 
can produce changes in chemical compounds. The 
current for such purposes may be generated in an 
electric cell, consisting, in its simplest form, of a 
beaker containing a fluid (usually sulphuric acid, or 
a solution of ammonium chloride) and two plates of 
different metals. The fluid acts more strongly upon 
one than upon the other, and there is consequently 



—11— 

generated electric force. The upper ends of tlie 
plate not immersed in the flnid, become charged with 
electricity, the zinc with negative and the other 
metal with positive, electricity. (Zinc and carbon 
are usually employed). This current may be con- 
ducted away from the ends ("poles") of the metals 
("electrodes"), through mres, thus one wire carrying 
the negative, the other the positive electricity. If 
these two wires are passed into a solution of an in- 
organic chemical compound, the compound may be 
decomposed. (See further under Solution ; Ions.) 



— 12 — 



Elements, Symbols, Valence. 

It has been stated that all matter consists of one 
or more elements. 

The more important elements are the following: 



letals) 




(Nonmetals) 




Potassium 


(K)' 


Oxygen 


(0)" 


Sodium 


(my 


Chlorine 


(Cl)' 


Lithium 


(Li)' 


Bromine 


(Br)' 


Barium 


(Ba)'' 


Iodine 


(J)' 


Strontium 


(Sr);; 


Mtrogen 


(N)"' 


Calcium 


(Ca)" 


Sulphur 


(S)" 


Magnesium 


(Mg)" 


Phosphorus 


(P) 


Aluminum 


(Al)"' 


Boron 


(B)" 


Manganese 


(Mn)" 


Carbon 


(C)" 


Zinc 


(Zn)" 


Silicon 


(Si)" 


Iron 


(Fe)" 


Hydrogen 


(H)' 


Lead 


(Pb)" 






Bismuth 


(Bi)'" 






Copper 


(Cu)" 






Silver 


(Ag)' 






Mercury 


.(Hg)" 






Gold 


(An)' 







Many of the elements do not exist in a free state 
in nature, because they possess an inherent tendency 
to combine with others ; this affinity is called chem- 
ical affinity. The union of like atoms forms a mole- 
cule of "simple matter;" the union of unlike atoms 
•a molecule of "compound matter." Elements pos- 
sessing a very weak chemical affinity are called "in- 
ert." — Symbols. For convenience when writing, the 
names of elements are abbreviated in a definite man- 
ner, so that a letter stands for the name of the ele- 
ment, (thus H for Hydrogen). For purpose of dif- 



— 13 — 

erentiation another letter may be added. (B for 
Boron; Ba for Barium). 

The Quantity of Combining Power, or Valence. 

The chemical combination of elements and their 
atoms always takes place in definite proportions. The 
combination between Hydrogen and Oxygen, for 
instance, is always in the proportion of two parts 
of hydrogen to one of oxygen, (or two atoms of hy- 
drogen to one atom of oxygen.) 

The ratio in which an element combines with one 
atom of Hydrogen, is called its Valence. Valance 
is, therefore, the quantity of combining (or replacing) 
power expressed in H units. 

Tor the purpose of demonstrating the combining 
power of elements, we assume that the atoms have 
bonds, or links, with which they link to the bonds 
or links of another element. Thus H has one bond, 

H , O two bonds. It is a law that when 

two atoms combine with each other, there must be 
produced an equal number of bonds for each of the 
combining elements. If the valence of one element 
is less than of the other, more atoms must be taken. 
To form the compound of H + O, water, it can only 
be accomplished by taking two H atoms, thus : 

H 

H O. When all the bonds are satisfied the 

compound is ^^saturated." By referring to the pre- 
ceding list of elements, the bonds have been indi- 
cated thus, O". 

Hydrogen is the unit for valence. If the combin- 
ing power of another element can not be studied 
from direct combination with hydrogen, its com- 
pound with some element may be studied the 
valence of which has been determined. Thus H 



7/ 



— 14 — 

does not combine directly with Na; but Na com- 
bines with CI to form ^aCl. CI has one bond, 
therefore ISTa must also have only one bond. 
Elements having the valence one are called Monads 
(univalent) ; those with valence II. Dyads (biva- 
lent) ; with the valence III., Triads (trivalent) ; 
with the valence IV., Tetrads (quadrivalent), etc. 

Variation of Valence. 

Under some conditions the valence of an element 
may vary. Thus an element having the valence I. 
may exhibit a valence of III., V., and VII. An 
element having the valence II. may exhibit the val- 
ence IV., VI. and VIII. The variation is with two 
bonds increase or decrease. This variation is ex- 
plained in this way : We credit the element with the 
highest number of bonds it ever exhibits, thus 
Chlorine, CP^^^. If two adjacent bonds were, tem- 
porarely to satisfy each other, there would finally 
be left only one valence CF; under certain con- 
ditions two or more adjacent bonds might be again 
opened, increasing the valence by two each time. 



Chemical Compounds. 

The chemical combination of two or more diiier- 
ent atoms forms a chemical compound. A chemical 
compound must be differentiated from a '^Mechan- 
ical Mixture" of two or more elements. In a mix- 
ture, the mixed elements may again be separated, 
unaltered, by physical means. But under suitable 
conditions their atoms may combine. Favorable 
conditions are such as allow an intimate contact 
with the molecules of the combining substances 



— 15 — 

This may be accomplished by dissolving the sub- 
stances in water, or by applying heat. 

Free elements exist in the form of molecules, that 
is, their atoms are linked to atoms of the same kind. 
While the selection between atoms is always most 
strongly exhibited between those of different kinds, 
when a simple molecule has once formed, this af- 
finity is not so strongly exhibited, (as in H H, 

H2). By the application of heat this union may be 
broken up, and then the bonds, temporarely free, 
will attract the bonds of different atoms that may 
be present likewise broken up, and a compound 

molecule will form, thus H H + CI CI + 

heat = H— H— + CI— + CI— = H CI + 

H CI. Single atoms of elements with free 

bonds, exist for that brief moment when they are 
separated from compounds, and this state is called 
the nascent state. Their chemical affinity is most 
marked in the nascent state. 

Compound Radicals. 

In a normal or saturated compound all bonds are 
saturated; it cannot combine with anything else, 
thus H 



O 



H V^ If now one or more of the 

composing elements were removed, there would be 

left a free bond, thus H ^^^O, or — H, 

or — OH. This rest of the compound is unsaturated ; 
it can combine vdth other elements and is called 
a compound radical. 

A compound radical is, therefore, an unsaturated 
rest of a chemical compound. 

Eadicals, as a class, terminate in yl, and are called 
according to the elements contained therein, or ac- 
cording to the compound of which they were part. 
Thus — OH is hydroxyl. 



7/ 



— 16 — 

Atomic and Molecular Weights. 

If HCl, hydrochloric acid, is analyzed, it will 
always be found to consist of one part of H and 
35.37 parts by weight, of CI. In other words one 
atom of H and one atom of CI have combined to 
form 1 molecule of HCl. The ratio of combination 
is hydrogen 1 and chlorine 35.37. These relative 
weights of the atoms, in the ratio of which the com- 
bine, are called their respective atomic weights. The 
total weight of the combined atoms (in the mole- 
cule) is the molecular weight. 



Classification of Elements. 

By referring to the list of elements it will be seen 
that they have been grouped as Nonmetals and 
Metals. Metals are usually solid at ordinary tem- 
perature. They are hard, and acquire a metallic 
lustre. The nonmetals may be solids, liquids, or 
gases at ordinary temperature. They do not possess 
the physical properties of metals. The nonmetals 
are acid-forming^ and the metals hasic, or base-form- 
ing elements. 

Classification of Chemical Compounds. 

Chemical compounds composed of two elements 
only are called ^^binary" compounds; those com- 
posed of three elements are called ternary com- 
pounds. The binary compounds are designated by 
naming the elements according to their order in the 
compound, terminating the last word with ide, thus 
KBr, Potassium hvoraide. 



— 17 — 

Acids y Bases and Salts. 

Chemical compounds may also specially be sub- 
divided into 3 classes : Acids, Bases and Salts. 

Acids. An acid is the chemical combination of H 
with and acid forming element. The acid forming 
elements are among the nonmetals. There are two 
groups of acids : binary and ternary acids. A 
binary acid is the direct union of H and the acid 
forming element. A ternary acid contains three ele- 
ments : H, the acid forming element, and oxygen. 
They are, therefore, sometimes called oxysLcids. 
Ternary acids are not formed directly, but indi- 
rectly by first forming from the acid forming ele- 
ment the acid forming oxide. This acid forming 
oxide, with water, forms the acid. For example : 

The acid forming element S forms SO2. 
SO2 + H2O = H2SO3. 

The acid forming oxides are sometimes called acid 
anlydrides, that is acids minus the w^ater molecuh.'. 

Different ternary acids from the same element. 

The intermediate product of ternary acids, the acid 
forming oxide, is in chemical character and compo- 
sition depending upon the valence of the acid form- 
ing element. The four oxides of S will therefore be 
as follows : (The acids are also formed.) 

S" + 0" = SO + H2O = H,SO, Hijposulphuwus. 

giy + 20'' = SO2 + H2O ^ H,SO. Sulphuro?^^. 

gvi + 30'' = SO3 + H2O = H2S64 Sulphuric. 

gvm + 40" = SO4 + H2O = H2SO5 Persulphuric. 

Nomenclature of Acids. 

Binary acids, example HCl, as a class have the 
prefix hydro, and the termination ic, thus hydro- 
chloric: HoS, hdrosulphuric, acid. 



// 



— 18 — 

Ternary acids are named according to valence of 
the acid forming element. Granting that an acid 
forming element exhibited only two valences, we 
would then call the lower valence acid, if the acid 
forming element were S, sulphuroi^s acid, and the 
higher, sulphuric acid. Where there are four dif- 
ferent valences exhibited, however, we designate 
the lowest valence acid by the prefix %po, and the 
highest valence acid by the prefix per, thus the ter- 
nary acids of S; lipyo^v\^h.-uxous, sulphuroi^s, sul- 
phuric and persulphuric, acid, (hypo, meaning ''be- 
low" (ous) and per meaning "above" (ic). The acid 
forming oxides are designated in the corresponding 
manner. 

Properties of Acids. 

Physical: Acids are gaseous, (dissolved in water) 
or liquids. They have a sour ("acid") taste, and are 
more or less caustic, destroying organic tissue. 

Chemical: Acids turn blue litmus paper red 
("acid reaction''^). The hydrogen may be replaced 
by a metal. 

Acid radicals. An acid may be said to possess 
two halves. The replaceable H, and the balance. 
This balance would be, without the H, the acid 
radical, thus — CI, the acid radical of hydrochloric 
acid (HCl) ; = SO^ the acid radical of sulphuric acid 
(H,SO,). 

Chemical Salts. 

A chemical salt is the union of a metal, (or basic 
radical) with an acid radical. In its simplest form it 
is produced when the H in an acid is replaced by a 
metal, thus : 

HCl + 'Nsi = NaCl + H. 



— 19 — 

The H need not necessarily be replaced by the 
metal in its free metallic state, but the metal may 
be obtained from its combinations, as will be shown. 
(See Bases, and Ions.) 

Denomination of Salts. 

A salt is designated according to the metal and 
the acid radical. Binary acids form salts designated, 
like binary compounds in general, by the termina- 
tion ide : ^a CI is sodium chloride. 

Salts of ternary acids are designated according to 
the acid radical. Thus of the acids of sulphur and 
sodium: iJ^/90sulphurows acid forms sodium Jiypo- 
sulpht^e. Sulphuroiis acid forms sodium sulphide. 
Sulphuric acid forms sodium sulphate. Persulphuric 
acid forms sodium persulphate. 

Acid, Neutral, and Basic Salts. 

When all the H in an acid has been replaced by 
the metal, we obtain a neutral salt ; (I^a2S04) when 
only part of the acid has been replaced we obtain an 
acid salt (]^aHS04), having still acid properties. 
Instead of speaking of them as acid salts (sodium 
acid sulphate), they are usually designated as fol- 
lows : Sodium &isulphate, sodium bicarbonate, etc. 

Bases are the hydrates of the metals, thus 'Na OH. 
The OH group or radical is derived from H — O — TL, 
water. Some bases may be formed by decomposing 
the water directly as of sodium : I^a + H — O — H — 
Na OH + H. Other elements form the hydrates by 
dissolving the hasic oxide in water, thus Ca O + 
H— O— H = (Ca (0H)2). 



— 20 — 

Formation of Salts from Acids and Bases. 

Bases may be divided into two halves of the mole- 
cule, the metal (basic radical) and the OH ^roup, 
thus ISTa OH = N'a— OH. 

When an acid acts upon a base, the H of the acid 
may be replaced by the metal of the base (see acids, 
thus : ^si OH + HCl = Na OZ + H OH, the nascent 
H of the acid, and the nascent OH group forming 
water. Thus an acid and a base form the corres- 
ponding salt. — 

The hasisity of an acid is its base neutralizmg 
power indicated by the number of the replaceable 
H in the acid. HCl. is monobasic. HgSO^ dibasic. 

The acidity of the base is the acid neutralizing 
power of the base thus 'Nsl OH is mono acid, Ca 
(0H)2 is diacid. 

(A basic salt is a salt, not neutral, still possessing 
basic properties.) 



Solution. Ionization. 



A solution is the homogeneous mixture of a solid 
or gas with a fluid. The substance undergoes solu- 
tion in the solvent ; the commonest solvent is water. 
The molecules of the dissolving substances pass be- 
tween the molecules of the solvent. If a solvent 
will dissolve no more of the substance it is called a 
saturated solution, a saturated solution may still be 
a solvent for another substance. 

Aside from the fine molecular division of the dis- 
solved substance, there is another change. The 
molecule is separated into its ions, hut not chemically 



— 21 — 

decomposed into its atoms. The ions are still part 
of a chemical combination. In binary compounds, 
(acids and salts), the ions correspond to individual 
elements and atoms, thus Na CI separate into 
sodimn ions and chlorine ions. The ternary com- 
pounds do not separate into the individual elements 
but into parts corresponding to the radicals; thus 
II2SO4 into II2 ions and SO4 ions, or ]N'a2S04 into 
jN'a2 ions and SO4 ions. The process of separation is 
called '^Dissociation'' of the molecule, or '^ioniza- 
tion." Dissociation is most complete in dilute solu- 
tions, and in certain solvents, of which water is the 
best. 

Electric Decomposition of Compounds. 

When an electric current is passed into a solution 
containing a compound dissociated into ions, the ions 
are attracted to the poles of the electrodes, some 
to the positive, and some to the negative pole. That 
is because the ions are electrically charged bodies. 
Unlike kinds of electricity attract each other ; there- 
fore the ions attracted to the positive pole must be 
electro negative, and those attracted to the negative 
pole, electro positive. Thus of IsTa CI, 'Na positive 
( + ) and the CI negative (— ) ; of Cl^O, CI +, 0— . 
Thus the compounds between any two elements have 
been studied; it has been found that an element may 
be positive in one compound, and negative in a differ- 
ent compound (see CI above). When the names of 
elements are arranged in a serial form according to 
their electro chemic character toward each other, 
we have the socalled electro-chemic series. It is of 
practical help by indicating which element in a 
compound should be written first, thus 'Nsl CI, and 
not CI N^a ; the positive element precedes. Further- 
more, an element may only change its valence when 



— 22 — 

it is electro-positive in a compound. Lastly, an 
electro-positive or electro-negative element may be 
replaced by one more electro-positive, or electro- 
negative, than the element in question. 
The electro-chemic series is as foUov^s: 
Oxygen, Sulphur, Mtrogen, Chlorine, Bromine, 
Iodine, Phosphorous, Arsenic, Chromium, Boron, 
Carbon, Antimony, Silicon, Hydrogen, Mercury, 
Silver, Copper, Bismuth, Lead, Iron, Zinc, Manga- 
nese, Aluminum, Magnesium, Calcium, Strontium, 
Barium, Lithium, Sodium, Potassium. 

Interchange of Ions, Double Decomposition, 

Law : Whenever there are present in the same 
solution ions necessary to form an insoluble com- 
pound, that compound will form. Being insoluble, 
it separates from the solution as a precipitate. 

In order to knov^ what ions will form insoluble 
compounds, one must know the insoluble compound. 
Thus it can easily be ascertained that Hgig is in- 
soluble. Therefore, if Hg ions and I ions meet in 
solution, the compound Hglg will form, thus 2KI '<" 
HgCl2 ~ IIgl2 "^ 2KC1. This interchange of ions 
is also called double decomposition. 

When acid and basic ions meet, there is likewise 
an interchange, a salt being formed : 

]!Ta OH + HCl =^ ITa CI + H— O— H. 



Deliquescence, Efflorescence. 

Some substances (solids) are so soluble in water 
that they attract water from the air when exposed. 



— 23 — 

and Kquify in it; they are said to be deliquescent. 
When water is phj^sically associated with a com- 
pound, as water of crystallization, (that is the water 
needed to form a crystal, or included in the crystal), 
it may lose this water of crystallization when ex- 
posed to the air; it is said to be efflorescent. 

Dialysis and Osmosis. Diffusion. 

All crystalline substances, when in solution, will 
pass out of this solution into water, when the water 
is separated from the surface of the solution by an 
animal membrane. Colloid substances do not pass 
out in this manner. The process is called dialysis. 

Osmosis is the passing of a current of water to- 
ward a concentrated solution of some salt, from 
which the water is separated by a membrane. 

Diffusion is the passing of one liquid into another 
of different specific gravity when the tw^o liquids 
form lawers one over the other. 



Chemical Formulae, Eeactions, Eeagents and 
Equations. 

A chemical formula is a collection of symbols stat- 
ing the composition of a compound. Thus ISTaCl 
is the chemical formula for sodium chloride ; H2SO4 
for sulphuric acid. 

A chemical reaction is the action of one substance 
with another, involving chemical changes. 

The substances taking part in a chemical reaction 
are called reagents. The written demonstration of 



— 24 — 

the changes, qualitative and quantitative, involved 
in a chemical reaction is an equation. 

Thus, the following equation demonstrates the 
chemical reaction between the reagents sodium hy- 
drate and sulphuric acid. 

2NaOH + H2SO4 = Na^SO^ + SH^O. 

An equation expresses Avhat actually takes place. 
It is not an equation if the quantities or reagents in- 
volved are not equal the sum of the products. When 
using a single element as a reagent the least that 
may be taken of it is a molecule. Thus it is proper 
to write 2H2 + 02 = 2H2O, and not 2H + O = 
H2O. 

H stands for one atom of H. 211 stands for 2 
atoms of H (H — , H — ,). H2 stands for one mole- 
cule (K H). 

Quantitative expression: A large figure preceding 
a symbol multiplies every part of the formula : thus 
2II2SO4 multiplies as follows: 4H, 2S, 8 — O atoms 
in the two molecules. A small figure following a 
symbol, multiplies the preceding symbol only ; when 
a formula is in parenthesis, a small figure following 
the parenthesis multiplies every element in the pa- 
renthises the same as when a large figure preceds 
the first element in the compound with or without 
parentheses. 



PART 11. 

INORGANIC 
CHEMISTRY. 



Chemistry is divided into ^'Inorganic" and '^Or- 
ganic" Chemistry. Organic chemistry considers 
compounds of carbon with H, O, 'N, 8, and P. These 
organic compounds are called '^carbon compounds.*' 
The compounds of all other elements belong to in- 
organic chemistry ; this is the first division of study. 

The study of the inorganic compounds necessi- 
tates a study of the elements that form these com- 
pounds. Occasionally these elements are in their 
free state of medical importance. 

For purpose of study elements may be grouped, 
according to certain points of resemblance in their 
character. It is convenient to arrange them as 
follows : 

I. The Nonmetals. 
H, 0, CI, Br, I, N, S. P, Si, C. 

11. The Metals. 
subdivided into: 

a) The Alkaline Metals: 

K, N'a, Li, (N'H^ group) ; 

h) The Alhaline Earths: c) The Earths: 

Ca, Sr, Ba; Type: Aluminum, Al; 

d) The remaining metals, ungrouped: 
Mg, Ag, Au, Cu, Hg, Al, Pb, As, Sb, Bi, Cr, Mn, Fe. 



— 26 — 

The Elements. 

Some elements occur in the free state in nature. 
Others only as chemical compounds. For purpose of 
demonstration elements chemically combined may 
be liberated. Chemical compounds may then again 
be formed from such elements. All chemical 
changes that occur must be carefully observed, and 
every step must he thoroughly understood. It con- 
tributes more than anything else to the habit of 
accurate observation and thinking. 



The Nonmetals. 



Hydrogen, Hydrogenium, Symbol H, Val. I, At. 
W. 1. 

Hydrogen does not occur free in nature to any 
extent ; mostly combined with water, forming 1-9 its 
weight. It is a colorless, odorless gas, lighter than 
air, insoluble in water. It is combustible (^^biirns") 
in air. It does not '^support" combustion of other 
elements. H is a constituent of all acids. It is of no 
direct medicinal use. 



Chlorine, CI, Val. I— VII, Atomic W. 35.3Y 

Bromine, Br, Val. I— VII, Atomic W. 79.76 

Iodine, I, Val I— VII, Atomic W. 126.53 

These three elements have been grouped together 

for convenience of study, because they have similar 

properties. There is a gradual increase in density. 

Chlorine is a gas; Bromine a liquid; Iodine a solid. 

Bromine and Iodine, are, however, easily volatilized. 

Note also the systematic increase in atomic weight. 



— 21 — 

Their chemical properties also resemble each other 
closely. With Hydrogen they form binary acids. 
They also form corresponding oxyacids. The salts 
of these acids have a close physical resemblance. 
Chlorine, Bromine and Iodine occur in nature com- 
bined as Chlorides, Bromides, Iodides and lodates. 

The following points are of particular interest : 

CJilorine. The most common ^preparation (salt) is 
Sodium Chloride, XaCl, or common table salt. It is 
a constant constituent of the animal tissue. Certain 
preparations are official, because they yield free chlo- 
rine : Chlorine water, chlorinated soda (containing 
chiefly sodium hypochlorite), chlorinated lime, 
(bleaching powder), containing calcium hypochlorite. 
Most chlorides are water soluble. Insoluble chlo- 
rides, PbCls, HgCl, IIg2Cl2. Chlorides do not act 
with their chlorine contents as free chlorine. The 
official binary acid is Hydrochloric Acid, containing 
about 32 per cent. HCl (dissolved in water). The 
commercial product, impure, is called muriatic 
acid. The ^'diluted hydochloric acid" is of 10 per 
cent, strength. 

The Chlorates are the salts of chloric acid, of 
interest is chiefly KCIO3. 

When heated it parts with its oxygen. It may 
likewise be decomposed when mixed with organic 
substances (Glycerine, Sugar, and also Sulphur), 
and when friction is applied to such mixtures. 
Dangerous explosions have thus occurred. 

Bromine. Preparations of medicinal interest, the 
bromides, chiefly KBr, Is^aBr, ^^H^Br, SrBr,. 
These bromides are soluble. (Insoluble Bromide, 
AgBr). 

Iodine. Insoluble in water. Soluble in alcohol 
and chloroform, and in solution of KI. 



— 28 — 

Preparations of Iodine. a Containing free 
iodine, Tincture of Iodine ; Compound Solution of 
Iodine, (Lugols Solution) ; Ointment of Iodine. 
h Certain organic preparations acting with liberated 
(available) Iodine: Iodoform, Thymol Iodide. Of 
the iodides there are official KI, STal, Hglg as the 
salts of chief interest. 

{Insoluble Iodides, Phis, Hglg, Agl). 

Note : I, CI, Br, are called Halogens ; their binary 
acids. Haloid acids. — 



Oxygen, Symbol 0, Yal. II, Atomic W. 15.88. 

Oxygen exists in the atmosphere mixed with 
Mtrogen, to form 1-5 of the volume of air. It abo 
forms, combined, 8-9 of the weight of water. 

Oxygen is a gas, odorless, tasteless, and slightly 
soluble in water. It combines more or less readily 
with most other elements, directly or indirectly, 
forming the oxides. Many substances burn in oxy- 
gen, that is, oxygen '^supports combustion." Oxy- 
gen supports also life, which is a process of contin- 
uous combustion within the tissues. 

Ozone is a special form of oxygen having 3 atoms 
to the molecule, 0^. It represents an especially 
active form of oxygen. 

Water, Hfi. The purest water is dilled water. 
Rain water, collected uncontaminated is also reative- 
ly pure. Spring water is usually contaminated with 
salts abstracted from the soil. When the impurities 
consist of carbonates (of Ca, Mg), which may be 
precipitated by boiling, we have a '^temporarely" 
hard Avater; if the sulphates of these metals are 



— 29 — 

present, it is permanently hard, because the impuri- 
ties can not be so separated. Mineral waters are 
spring waters that contain relatively large amounts 
of salts in solution. They may, therefore, be of 
medicinal interest. 

Water is a solvent for many substances. It forms 
a necessary part of the food supply of living beings. 

Hydrogen dioxide, II2O2 is the chemical imion of 
two hydroxyl groups OH OH. 

It is an ingredient in the official luater of Hydro- 
gen dioxide. The compound is easily decomposed, 
sometimes vdth explosive violence, yielding free 
oxygen (H2O2 = H2O + O). 

Note. The process of uniting with oxygen is 
called ^^oxydation;'' substances that yield free 
oxygen are called "oxydizing agents.^' Substances 
that take away oxygen from compounds are called 
^ ^reducing agents.'' 



SuLPHUH, S, Valence II— YIII, Atomic W. 31.83 

Sulphur occurs in a free state, and may be kept 
unchanged. It is a solid, of yellow color, insoluble 
in ordinary solvents ; soluble in oils, and CSg. 
When exposed to air, it forms traces of SO2 and H2 
SO4. It is sometimes used in medicine in its free 
state. 

Compounds of importance : H2S, hydrosulphuric 
acid. Many metallic salts, suphides, are insoluble, 
and its is, therefore, a useful reagent in chemical 
analyses. — 

SO2, produced when sulphur burns in air, is a strong 
disinfecting and bleaching agent. 



— 30 — 

H2SO4, sulphuric acid, is one of the strongest 
acids we have. It liberates most other acids radi- 
cals from their compounds. It is 1.8 times heavier 
than water; because of its heavy, oily appearance 
it is called '^Oil of Yitrol." Its salts are the sul- 
phates. Of importance are K2SO4, ]N'a2S04, Zn 
SO4 (White Vitrei), FeSO^ (Green Yitrol), Cu 
S04 (Blue Vitrei). 

(Insoluble sulphates, CaSo4, PbS04, BaS04). 



]^iTEOGEN, ]^, Valence III — V, Atomic W. 13.93. 

Mtrogen forms 4-5 of the air. It shows little 
chemical affinity for other elements (it is "inert^'). 
As an element it is of no medicinal importance. 

Chemical compounds. The union of IST and H 
forms Ammonia, NII3. As a compound it resembles 
in many respects the bases (Metals), and is, therefor, 
frequently classed with them. With water it forms 
NH, + H2O = NH4 OH (Ammonium hydrate). 
The radical Ammonium, ISril4, — combined with acid 
radicals, yields corresponding salts (NH4 CI). Am- 
monium is a volatile base, and the salts are more or 
less volatile. Important Ammonium Salts are 
(^114)200^^. NH^Cl. — The volatile ammonium base 
may be liberated by a stronger, fixed, base : ]^Il4Cl 
+ KOH = -^Hfill + KCl. 

NII4OII, dissolved in water, yields Ammonia 
water, (10 per cent, strength). A 28 per cent, solu- 
tion is called the Stronger Water of Ammonia. An 
alcoholic solution of NHo is called Spirit of Am- 
monia. 

Nitrohydrochloric Acid, is prepared by mixing 
HN'Og and HCl. It contains free CI and jSTHrosyl 



_„ 31 — 

chloride. It is called "Aqua Eegia," because it is 
the only acid dissolving gold, due to the free (nas- 
cent) chlorine. — All neutral (normal) nitrates are 
saluable in water. 



Phosphorous, Symbol P, Val. Ill — V, Atomic W 
30.96 ' 

Phosphorfius is a solid, wax like substance. It 
does not occur free in nature, but is obtained from 
the phosphates (of bones). It m^ust be kept under 
water, because, in its free state, it inflames when 
coming in contact with air. Phosphorous is insolu- 
ble in water, it is soluble in carbon bisulphide, 
chloroform, absolute alcohol, and in fatty oils. The 
oxides of Phosphor(^us P2O3 and P2O5 form Phos- 
phorous and Phosphoric acid, respectively. The for- 
mation of the oxyacids from Phosphorous is irregu- 
lar, and can not be discussed here. There exists also 
a Hypophosphorous acid. Of interest are chiefly 
the medicinal preparations and salts called the Hypo- 
phosphites (of 'Nsi and Ca), and the phosphates (of 
^N'a and Ca). 



Boron, B, Val. Ill, Atomic W. 10.9. 

Boron is found in nature comhined in Borax and 
Boric acid. The acid itself is of medicinal interest. 
It has mild antiseptic properties. The salt, Sodium 
borate, or borax, is largely used in medicine for an- 
tiseptic purposes. 



Carbon, C, Val. II— IV, Atomic W. 11.97. 
Carbon is a widely distributed element. It is best 
knoAvn as Charcoal. There are other forms of Car- 



— 32 — 

bon, more or less pure, such as Coal, Graphite, and 
the Diamond. The latter is the purest crystalline, 
form of Carbon. — Carbon, in the form of Charcoal, 
absorbs gases readily when dry. Burned in the air. 
Carbon forms CO2. The acid, H2CO3, is Carbonic 
acid. It is volatile and possesses weak acid proper- 
ties. — Carbon is a constitutent of all organic matter. 
Charcoal is obtained from animal tissue (animal 
charcoal,) and from any wood, (Willow charcoal) 
when either is burned with insufficient access of air, 
Organic substances '^char." Carbon is the basis of 
the Carbon compounds (Organic chemistry). 



The GrAS Flame and the Bunsen Burner 

Illuminating gas is a mixture of various gases 
rich in Carbon. When the gas is lighted as issuing 
from the jet, the separate constitutents of the gas, 
C and H, undergo combustion in the air, forming 
CO2 and II2O. I^ot all of the Carbon undergoes 
combustion, but the surrounding heat renders these 
carbon particles incandescent. If air is mixed with 
the gas before it is ignited, enough oxygen is sup- 
plied the gas, that all the carbon is consumed, and 
more heat, but no light, is produced, therefore a 
blue flame (Bunsen Burner). 



— 33 — 

The Metals. 

The Alkali Metals. 

The Alkaline Earths, 

The Earthy Metals. 

The Heavy Metals. 

The Alkali Metals. 
Potassium, (Kalinin) K, Val. I, Atomic W. 39.1. 
Sodium, (JSTatriiun) E'a, Yal. I, Atomic W. 23. 
Lithium, Li, Val. I, Atomic W. 7.01. 

The alkali metals are so called because of the 
strongly alkaline character of their hydrates. These 
metals have several properties in common; they do 
not exist in their free state in nature ; they are soft 
and wax-like in consistency. They decompose water 
readily, forming free H and the hydrate of the 
metal (K + H— O— H = KOH + H). Their oxides 
are not stable, but tend to form hydrates energeti- 
cally when coming in contact with moisture. The 
salts of the alkaline metals are practically all solu- 
ble in water, including their carbonate and phos- 
phates (except those of Li). — There is a close physi- 
cal resemblance, and similarity of properties and 
actions, between the corresponding salts of these 
metals. — As a rule, the hydrates, carbonates and 
phosphates of these metals will precipitate out of 
solution the salts of the other metals, when they are 
mixed with solutions of their soluble salts. (Li- 
compatibility, example, ZnS04 + [N'aaCOg — ZnCOg 
+ ]S^a2S04).— 

Potassium. Important preparations and salts. 
KOH, {Potassium hydrate, Potassa, in Solution of 



— 34 — 

Potassa. K^CO^, (Potassium corhonate, ■ Sal Tar- 
tar). KHCO^ Potassium bicarbonate, KCIO^, Potas- 
sium chlorate. KBr, Pot. Bromide. K2SO4. Po- 
tassium sulphate. KE'Og, Potassium nitrate (Salt 
petre). KMn04, Potassium permanganate. KI, 
Potassium iodide. 

Sodium, preparations and salts of importance: 
J^aOH, Sodium hydrate, Soda. NagCOg, Sodium 
carbonate, (Washing Soda). E^aHCOg Sodium bi- 
carbonate, (Baking Soda). !^aCl, Sodium chloride, 
(Table Salt). Nal, ^^aPr. '^s.^^O^, Sodium sul- 
phate, (Glauber's Salt). NaNOg. 

Note: Whenever the solution of a bicarbonate is 
boiled, it is changed into a carbonate by giving off 
H2CO3, thus, SNaHCOg+heat^ISra^COs+HoCOs. 



The Alkaline Earth Metals. 

Calcium, Ca, VaL II, Atomic W. 39.91. 
Strontium, Sr, VaL 11. Atomic W. 87. 3. 
{Magnesium, Mg, Val. II, Atomic W. 24.3.) 
Barium, Ba, Val, II, Atomic W. 136.9. 

The members of this group are so called, because 
they resemble the alkaline metals on the one hand, 
and the earthy metals on the other. 

They resemble the alkaline metals, in that the 
metals can not be kept, unprotected, in a free state. 
They do not occur in nature in a free state. The 
metals will decompose water, but not so readily as 
the alkali metals. Their oxides form hydrates, with 
water, with more or less readiness ; they have, there- 
fore, an '^alkaline" character. In general, it may 



— 35 — 

be said, that they are less energetic than the alkali 
metals. 

They resemble the earthy metals, in that their ox- 
ides have greater stability than the oxides of the al- 
kaline metals — they do not form the hydrates as 
readily when coming in contact with water. Their 
carbonates and phosphates are insoluble in water. — 
The metals of the alkaline earth group show, there- 
for, a gradual tendency to transition, in their chem- 
ical properties, toward the group of earthy metals. 

Calcium, important preparations and Salts : 

CaO, Lime, when coming in contact with water, 
slaTces, i. e. it forms Ca(0H)2, thus CaO+H—O — H== 
Ca(OH)2. Ca(OH)2 is sparingly soluble in water, 
forming "Lime water." CaCl2 (Calcium chloride) and 
Chlorinated lime are chemically two distinct com- 
pounds. Chlorinated Lime is lime charged with chlor- 
ine, forming, among other compounds, calcium hypo- 
chlorite, which, upon exposure to air, or more readily 
upon the addition of acids^ liberates (available) chlor- 
ine. 

CaSO^ + 5% of water. "Dried Calcium Sul- 
phate." Calcium sulphate, commonly called Plaster of 
Paris. It is native Gypsum, dried to 5% of water. 
If it contains more, or less, water it will not ''set," that 
is, harden, when it is again mixed with water. 

(Calcium Carbonate and Calcium Phosphate are in- 
soluble in water.) 

Calcium phosphate forms the Chief mineral (solid) 
constituent of bone. Deficiency in this salt in bone 
leads to a softening of bone. 



— 36 — 

Strontium and Barium, and their salts do not possess 
great medicinal interest. The Strontium bromide is 
sometimes used to replace KBr, and NaBr. 

Ba(OH)2 in solution forms the Baryta water. 
BaSO^ is of chemical interest^ because it forms a very 
insoluble sulphate, and is therefore used to test for 
H2SO4 or its salts. 

Magnesium is not usually classed with the alkaline 
earths, but it is considered here as a matter of conveni- 
ence. It may be said to incline still more, than the 
other members of this groups toward the earthy 
metals. When ignited Mg burns in air to form MgO, 
the particles being rendered incandescent, producing a 
most brilliant (flash) light. 

MgO, Magnesia, is usually called Calcined Magnesia, 
because it may be prepared by igniting the carbonate, 
thus MgCOg+heatuzMgO+CO^. (Note: "Calcina- 
tion" is the process of igniting a carbonate, and pro- 
ducing an oxide.) There is also a heavier, denser, 
form called "Heavy Magnesia." It does not form the 
hydrate readily when coming in contact with water ; 
it is insoluble. (Note, insoluble oxides, in contact with 
water, act as hydrates, Mg(OH)2, and any other 
hydrate that cannot be formed directly by dissolving 
the oxide in water, may be formed indirectly by pre- 
cipitating a soluble salt with another hydrate, thus 
MgS04+2NaOH=Mg(OH)2+Na2S04.) 

MgSO^, Magnesium sulphate, is commonly called 
Epsom Salt, because it is found in the Springs at 
Epsom. 



37 — 



The Earths. 

Aluminum, Al, 27.04 Atomic W. Val. III. 

Aluminum is the commonest and typical representa- 
tive of the group of earths. The other members are of 
only scientific or technical interest ("the rare metals.") 

Aluminum is found in nature as an earth or clay, 
(hence the name "earthy metals"), as an oxide or 
hydrate. The metal itself is well known. It is exceed- 
ingly light, and does not rust upon exposure to air. 

Aluminum hydrate, Al2(OH)g forms when a sol- 
uble Aluminum Salt is precipitated by Sodium Carbon- 
ate. It must be distinguished from Alum (Alumen), 
and from Aluminum Sulphate. 

Alumens, as a class, are double salts (two different 
bases) one of which is Al. Thus we have a Potassium 
Alum, Ammonium Alum, and Iron Alum, according as 
to whether Potassium, Ammonium, or Iron is asso- 
ciated as a base with the Aluminum. The official Alum 
is the Potassium Alum. 

Aluminum and Potassium Sulphate. 

There is not infrequently substituted the Ammonium 
Alum. The latter may be detected by adding to a solu- 
tion of the Alum, a solution of KOH, when the Am- 
monium, if present, is liberated. All alums contain a 
large percentage of water of crystallization (24 Mole- 
cules). When Alum is dried, it increases in strength 
accordingly, and is then called "burnt" or dried Alum. 



— 38 — 

The Heavy Metals. 

The remaining metals are so called, because of their 
relatively heavy specific gravity (All over 6.) Most of 
them are well known in their free state, and when 
kept dry, do not easily rust or tarnish. Metals like 
Gold, Silver, and Platinum do not rust at all, and are, 
therefore, called *'noble metals." These metals do not 
desompose water except at very high temperatures. 
Their oxides are not soluble in water and do not form 
hydrates, but in the presence of water act as hydrates. 
Their carbonates (and some other salts) are insoluble 
in water. The members of the group of heavy metals 
have marked metallic properties. 

The heavy metals are found in nature either as free 
metals, sometimes associated with other metals, or as 
sulphides or oxides, and may be separated from these 
compounds by proper chemical methods. (They are 
said to occur as ores^ and are found in mines.) 



Zinc. Zn, Atomic W. 65. 10. Val II. 

Preparations and Salts: ZnO, Zinc Oxide. ZnCOg, 
Zinc Carbonate. ZnSO^, Zinc Sulphate (White Vit- 
riol). ZnCl^, Zinc Chloride. 



Silver (Argentum) Ag, Atomic W. 107.66. Val I. 

Preparations and Salts: AgNOg, Silver Nitrate. 
Solutions of Silver Nitrate must only be prepared 



— 39 — . 

with distilled water. Any organic matter reduces a 
solution of Silver Nitrate to Silver Oxide and Metal- 
lic Silver. The water must be free from Chlorides 
(insoluble AgCl.) The solution must be preserved 
protected from light. — Diluted Silver Nitrate is the 
salt mixed with Potassium Nitrate. Fused Silver 
Nitrate is prepared in stick form, to be used for cauter- 
izing purposes. It contains a trace of AgCl to toughen 
the mass. (No solutions of organic substances should 
be mixed with solution of Silver Nitrate.) 
{Insoluble salts, AgCl, AgBr, Agl.) 



Copper, Cu. Atomic W. 63.18. Yal. II. 

Preparations and Salts: CuSO^, Copper Sulphate. 
(Blue Vitriol, Blue Stone.) 

(Fehling's solution consists of CuSO^ and Potas- 
sium Hydrate and Potassium and Sodium Tartrate, 
dissolved in water). • 



Mercury, Hydrargyrum. Val. II. Atomic W. 199.6. 

Mercury is the only liquid metal we possess. At a 
very low temperature it solidifies, however. Metallic 
Mercury is sometimes used in a free state. 

Preparations and Salts: Some preparations con- 
tain free Mercury: Mercury with Chalk, and the 
Mass of Mercury, for internal administration — The 
Ointment of Mercury for external application. — 
Hg2Cl2 Calomel, Mild Mercurous chloride (Subchlo- 
ride of Mercury). 



— 40 — 

HgCl2, Corrosive Mecuric chloride, Corrosive Sub- 
limate, Bichloride of Mercury. Poison! 

Calomel must be carefully distinguished from the 
Corrosive Sublimate. The english official names have 
been fixed for the purpose of avoiding errors. Calomel 
is an insoluble powder. Corrosive Sublimate a crysal- 
line solid, soluble in water. Calomel is comparatively 
nontoxic; Corrosive Sublimate very toxic. 

Calomel must not be exposed to strong sunlight, 
nor mixed with chlorides, that conversion to Mercuric 
Chloride may not occur. Corrosive Sublimate may be 
detected as an impurity in Calomel, by dissolving, or 
mixing the powder with water, filtering, and testing 
the filtrate with KI : HgCl2 will form red precipitate 
Hgl2, soluble in excess of either reagent. There are 
also official : a Mercurous Iodide, Hg2l2 and Mercuric 
Iodide Hgl2. — 

The red and yellow Mercuric Oxide are chemically 
identical ; the red oxide is a crystalline substance, the 
yellow oxide an impalpable powder, and therefore more 
suited for ointments. 

(The yellow subsulphate of Mercury is called ''Tur- 
peth Mineral.") 



Lead, Plumbum, Pb. Atomic W. 206.4. Val. II. 

Preparations and Salts: PbO, Lead Oxide, Lith- 
arge. Lead Oxide possesses, of course, basic properties. 
When this base is used to decompose an oil, it forms an 
insoluble soap — a Lead Soap, used as "Lead Plaster." 

Pb (C2H302)2 Lead acetate, (organic acid salt) is 
commonly called "Sugar of Lead" because of its sweet 



— 41 — 

taste. It dissolves, when in solution, a certain amount 
of PbO, forming a solution of basic lead acetate, or 
"Goulard's Extract." A diluted solution of basic lead 
acetate (lead subacetate) is called ''Lead Water." 



Arsenic, As. Atomic W. 14.9. Val. III. 
Preparations and Salts: AS2O3. Arsenic Trioxide, 
"Arsenic," forms with water, and when heated together 
with a base, or soluble carbonate, an arsenite, thus Po- 
tassium Arsenite, a solution of which is called "Fow- 
ler's Solution," containing 1% of the salt, Potassium 
Arsenite. 

(AS2O3 is a common ingredient in poisonous prepar- 
ation for the extermination of mice and rats. The ease 
with which it is obtainable in this form makes it a fre- 
quent cause of suicide and attempts at poisoning. Ars- 
enic may be detected in inorganic mixtures by adding 
Zinc and HCl, generating Hydrogen, which will com- 
bine with arsenic, forming the volatile AsHg.) 

The official chemical antidote is the Hydrated Ferric 
Oxide with Magnesia, prepared by mixing a solution 
Ferric Sulphate and a solution of Magnesia. The 
Arsenic combines with the Hydrate of Iron formed, to 
form an insoluble Arseniate of Iron.) 



Antimony, (Stibium) Sb. Atomic W. 119.6. Val. 
III. 

Preparations and Salts: Sb203, Antimony Oxide. — 
Antimony Sulphide, Pb2S3. Sulphurated Antimony, 
or "Kerme's Mineral." 



— 42 — 

A solution of the SbClg is called "Butter of Anti- 
mony," and is sometimes used as a caustic application. 



Bhmuth, Bi, Atomic W. 208.9. Val. III. 

Preparations and Salts: The common medicinal bis- 
muth salts have one property in common : they are in- 
soluble in water; furthermore, they are basic salts. 
Thus we have Bismuth subnitrate, (BiO)N03H20 and 
Bismuth subcarbonate, (BiO)2C03H20. These basic 
salts are formed when the neutral salt comes in contact 
with water. 

(A dangerous impurity occasionally found in Bis- 
muth and its salts^ is Arsenic.) 



Chromium. Cr. Atomic W. 52. Val. II-VI. 

Preparations and Salts: CrOg, commonly called 
Chromic Acid, is Chromium Trioxide, acid forming. 
Its salts are the Chromates: Potassium Chromate, 
and Potassium Bichromate. 



Manganese. Mn. Atomic W. 54.8. Val. III. 

Of interest only are the salts called permanganates 
(Potassium permanganate). Mn is an example of a 
metal which may become an acid-forming element 
when acting with the highest valence. The perman- 
ganates are oxydizing agents, because in acid and 
alkaline solution they will yield oxygen to other sub- 
stances. — 



— 43 — 

Mn02, Manganese Dioxide, is found in nature as a 
common source of Manganese. (Solutions of Potas- 
sium Permanganate must always be prepared with dis- 
tilled water, to prevent reduction of the salt by organic 
matter.) 



Iron, (Ferrum.) Fe. Val. II-VI. Atomic W. 55.88. 

Iron is one of the best known metals. It is widely 
distributed in nature, and is a constituent of all animal 
tissue (Haemoglobin.) It is of some interest to note 
the different kinds of iron, commercially and tech- 
nically : Cast Iron, containing about 5% of Carbon, 
and a trace of Manganese and Phosphorus. Spiegel- 
eisen, a manganese containing iron. Wrought Iron, 
containing only a trace of Carbon, and must be free 
from Phosphorus. Steel is iron containing about 1% 
of chemically combined Carbon ; it is, according to the 
method of preparing it, more or less brittle. 

Preparations and Salts: Metallic Iron is official as 
Reduced Iron, a pure, powdered form of Iron. The 
salts may be divided into two classes, the Ferrous and 
Ferric Salts, (Val. II and IV respectively.) Ferrous 
salts easily become oxidized to Ferric salts. Such 
changes may be prevented through admixtures of 
sugar to the preparation. 

The chief Ferrous Salts are : Ferrous Carbonate, 
Ferrous Sulphate and Ferrous Iodide. The chief Ferric 
Salts are: Ferric Chloride (Solution and Tincture), 
and the Ferric (sub) sulphate (Solution and Powder, 
"MonselFs.") 



— 44 — 

Chemical Incompatibility. 

When two compounds cannot be mixed in solution 
without losing their character, and without being de- 
composed, they are chemically incompatible. 

Incompatibility exists: a) between compounds form- 
ing an insoluble, new compound, b) Between salts 
and acids, when the acid is stronger than the acid 
(radical) of the salt, and will replace the weaker acid, 
c) Between a salt and a stronger base, which will re- 
place the weaker base. 

d) Between acids and bases, in general. 

(Prescriptions may be written with the view of ob- 
taining the new compounds formed.) 

Insoluble Salts: (The oxides, hydrates) carbonates 
of the earthy and heavy metals ; CaSO^, Magnesium 
Phosphate. Zinc Phosphate, PbSO^, PbCl2, Pbl2, 
Hgig, Hg^Cl^, AgCl, Agl, AgBr. Iron Salts and Tan- 
nic Acid. 

b) Inorganic acids liberate organic acids from salts. 
Any acid liberates Carbonic Acid from its salts. 
Sulphuric Acid liberates any inorganic acid. 

c) KOH, NaOH, Ca(OH)2 liberate NH^ OH. 
Oxidizing agents are incompatible with substances 

which they oxidize. 



— 45 — 
Chemical Analysis. 

A chemical analysis is the process of "taking apart" 
a mixture or a chemical compound, to determine its 
composition. 

It presupposes definite knowledge of the character of 
the substance one is trying to detect ; the analysis con- 
sists in bringing about certain changes that would in- 
volve the substance looked for, in a definite manner 
The first step is always physical inspection and the 
determination of physical properties of the substance 
under investigation, such as solubility, odor, taste ; one 
may at times identify substances by these means. 

The substance to be analysed may first be tested for 
organic substances by charring. Having determined, 
say, that only inorganics are present one may generally 
proceed as follows : 

I. Dissolving the material in water, hot or cold. 

II. Remove any insoluble part by filtration, and re- 
serve it for testing. 

III. The filtrate may be tested: a) by acidifying a 
part with HCl, and passing H2S through it, or b) by 
passing H2S through it after making it alkaline with 
NH4OH, c) or one may add a soluble carbonate to the 
solution. 

If under III, a-b-c, a precipitate forms, these consist 
of metallic sulphides or carbonates which are insoluble. 
The precipitate must then be identified by further test- 
ing. (More or less elaborate schemes are found in 
various text books of Chemical Analysis, to which the 
student is referred.) 



— 46-- 

If no precipitate forms, the metals, with the excep- 
tion of the alkaU metals, may be considered absent. 

Potassium, in the absence of Na and organic matter 
may be tested for by the flame test; if K is present, 
a violet flame. 

Sodium colors the flame strongly yellow. 



The Determination of Acids. 

If the nature of the bases present has been deter- 
mined, certain acids may be excluded, thus all the acids 
that would form with the bases insoluble compounds, 
and vice versa. Certain acids may then be tested for 
directly, that is, their ions may be precipitated from 
solutions by reagents that would form insoluble com- 
pounds. H2SO4 may be precipitated with BaCU ; HCl 
with AgNOg ; KI with HgCl^. 



Direct Methods of Testing for Bases. 

The preliminary tests having been made as outlined, 
some bases may be tested for, directly. The principle 
here again is the formation of insoluble compounds, by 
bringing together the ions that will form insoluble com- 
pounds. Thus Ca ions may be removed from solutions 
by soluble sulphates, or better, by oxalates or car- 
bonates. 

Fe ions may be precipitated as the Ferric hydrate or 
FeS ; Ag ions by soluble chlorides as AgCl. Ammo- 
nium may be liberated from its salts by KOH or 
NaOH. 



-- 47 -^ 

Quantitative Chemical Analysis. 

Quantitative Chemical Analysis has for its object the 
determination of the quantities of the substances under 
investigation. It may be gravimetric or volumetric. 

Gravimetric Analysis determines the amount present 
by directly weighing its quantity. An accurate chem- 
ical balance is the first requisite. The underlying prin- 
ciples are very simple. First the substance must be 
separated in such a form that it can be weighed. 
Second, the form of the compound must be sufficiently 
stable to be definite. 

An example : The object is to determine the quan- 
tity of NaCl present in a solution. 

The method consists of removing the CI in weighable 
form, from the molecular weight of NaCl we know the 
amount of NaCl that existed, if the quantity of CI is 
known. It is weighed as AgCl. The process is as fol- 
lows : To the solution is added AgNOg until a precipi- 
tate (of AgCl) no longer forms: Ag^Og+^^Cl^ 
AgCl+NaNOg. The precipitate is filtered, washed, 
and dried. If the weight of the filter paper is accurate- 
ly known, the filter with contents of AgCl may be 
weighed; otherwise it is best to burn the filter paper 
by introducing the precipitate AgCl with filter into a 
crucible and igniting at a lozv heat, until the paper is 
consumed, and weighing the residue. Granting that 
1.43 grams of AgCl were formed, the moleculer weight 
of AgCl is (Ag 107.66+Cl 35.37) =143.03. If 143.03 
AgCl contain 35.37 grams CI, 1.43 contain 0.3537 CI 



— 48 — 

(= found). Then, the molecular weight of NaCl is 
(Na 23 + CI 35.37)=58.37. 

35.37 : 58.37 : : 0.3537 : X =0.58S' N"aCl. 

Volumetric Analysis. 

This method of quantitative analysis measures by 
volum the quantity of the substances. 

When an acid is thus determined, it is acidimetry ; 
when an alkali is so determined is is alkalimetry. 

The underlying principles of the method are the fol- 
lowing, as shown in the volumetric estimation of HCl : 
NaOH+HCfcNaCl+H^O. 
40+36.37=58.37+18. 
That is, one molecule, or 40 parts, of NaOH^ will neu- 
tralize 1 molecule HCl of 36.37 parts. A solution is 
therefore prepared containing 40 grams NaOH in 1000 
Cubic centimeters. This is called a "Normal" solution. 

The whole amount would neutralize then 36.37 
grams HCl, or 1 Cubic centimeter 1/1000 of 36.37 HCl, 
or 0,03637 grams. 

The normal solution of NaOH is now added to the 
solution of HCl until it is neutralized; every cubic 
centimeter equals 0,03637 HCl. To determine when 
the neutral point has been reached, an indicator is used, 
such as litmus, or phenolphthalein. 

Note: A normal solution contains the molecular 
weight in grams to 1000 cubic centimeter; a deci- 
normal solution 1/10 the molecular weight. Moreover, 
the molecular weight is divided by the acidity of the 
base, or basisity of the acid, thus H2SO4 contains ^ 
the molecular weight to the liter, it having 2 replace- 
able H, dibasic. 



PART 111. 



ORGANIC 
CHEMISTRY 



Organic Compounds. 



Organic Chemistry is the study of the Carbon Com- 
pounds — Compounds of Carbon with Hydrogen, in- 
cluding, sometimes, Oxygen, Nitrogen, Sulphur, Phos- 
phorus. 

When an inorganic compound is heated with air, 
("ignited") it either volatilizes or, (usually), leaves 
an ash, but it does not char (=become carbonized). 

Organic compounds, when ignited, become charred 
because of the excess of Carbon present ("charcoal"), 
but when pure, organic compounds are finally com- 
pletely consumed without leaving ash. 

The inorganic compounds were exceedingly simple, 
— the organic compounds may be very simple or most 
complex. The classification of organic compounds 
will be developed in detail in the subject matter. They 
may be classified in various ways. We shall also meet 
with acids, bases and salts as in inorganic chemistry. 



— 50 — 

In all organic compounds C acts with the valence 
IV, illustrated thus : j 

— c — 

/ 

Formation of Organic Compounds. Formulae. 
Open Chain Series. 

The simplest organic compound possible would be 
H 

C^^H^^, or H — C — H. It is a saturated compound. 

H 
All other compounds are derivatives from this com- 
pound, and, of course, they may only be formed by sub- 
stitution of some other element, or radical, for one or 
more hydrogens. If one or more H in that compound is 
taken away, there remains the compound radicaL CH^ 
is a definite compound ; so is every new product formed 
by substitution as stated. These new compounds are 
called Derivatives, 2iS a class. 

If the radical CH3 — is linked to a second radical, 
CH3, a new compound is, of course, formed, having 
this formula : CH3.CH3 ; the period between the rad- 
icals indicates their combination. The formula is a 
''Graphic Formula/' because it describes the formation 
of the compound. 

CgHg is an identical formula as to percentage com- 
position with the preceding. It teaches nothing as to 
the method of formation^ and is called an empiric 
formula. 



— 51 — 

CH3.CH3 is a compound; CH3.CH2 — would be a 
radical. Another CH., — may be linked on, to form 
the new compound CH3.CH2.CH3 ; a similar linking 
might be carried on indefinitely. Thus a perfect chain 
would be formed, 

H HHHHHHHHH 

I I I I I I I I I I 

H— C C— C— C— C— C— C— C— C— C— H 

I I I I I I I I I I 

H HHHHHHHHH 

This chain may be opened at both ends, to form by 
substitution, new compounds. The compounds of this 
series are called "Compounds, or deviatives, of the 
open chain series." 

Addition Compounds. 

The linking may also take place in this way: 
H H 

I I 

C==C, that is the linking between the radicals may 

I I 

H H 

be double. Under certain conditions one of the double 

links may be broken up and taken up by a new element, 

or radical. In such a case a new compound may be 

formed by addition, and substitution. 



— 52 — 

The Closed Chain Series. 

As a basis for this series, six carbons are linked in 
this way: 




b 



II 



This compound so arranged is called a nucleus, 
(from which other compounds may be formed). Every 
alternate carbon may also be linked to its neighbor by 
a double bond, giving then rise to the compound CgHg. 
(Name, Benzene.) 

Derivatives: Where the linking takes place by single 
bonds only^ as in C^. H^gj substitution derivatives only 
are possible ; with double links, addition compounds, 
as well as substitution derivatives, are possible. 

When, in C«H,„, an H is removed, it leaves the 
radical C^jH^ ^ — ; this may be linked to a radical, say 
CH3 — , to form CgHj^.CHg; now, new compounds 
may be formed again by further substituting for one 
or more H remaining in the nucleus, or by substituting 
an H in the CH3 — radical : The former would be 
substitution within the nucleus ; the latter within the 



— 53 — 

**side chain" (CHg — ). The compounds would have 
the same empiric formula, but would be of different 
chemical character, thus: CgH^Q.OH.CHg (nucleus 
derivative OH) and CgH^^.CH2,OH (side chain de- 
rivative OH). 



The Open Chain and its Derivatives. 

The first compound in the chain is CH^. It is called 
"Methane." (The series is called also, the "Methane 
Series.") Its first radical is CH3 — , called Methyl. 
CH3.CH3 is "Ethane." CHg.CH^— radical, Ethyl. 
CH3.CH2.CH3 Propane. CHg.CH^.CH^.CHg is Bu- 
tane. All these compounds are composed of C and H ; 
they are called Hydrocarbons. 

Importance of the Hydrocarbons. The Hydrocar- 
bons form the chief constituents of crude petroleum. 
The smaller the number of C atoms in the molecule, 
the more liquid or volatile they are, and vice versa. 
Thus CH4 is a gas, CqH^^ a liquid, C2oH^2 2. solid. 
The lighter Hydrocarbons include Benzine, Coal Oil, 
liquid Petrolatum ; the heavier Hydrocarbons, Petrolat- 
um (vaseline), Paraffine. These are of an oily char- 
acter, or fatty. They do not decompose and become 
rancid! "Paraffine" is one of the heaviest Hydrocar- 
bons. 

Derivatives of importance: CHCI3, Trichlormethane, 
or Chloroform, and CHI3, Triiodomethane, or Iodo- 
form. Iodoform liberates nascent Iodine when it is 
brought in contact with tissue secretions (wounds), 
and is an antiseptic. 



— 54 — 

Alcohols, Aldehydes, Acids. 

Alcohols are the hydrates of hydrocarbon radicals. 
Thus CH3.OH, CHg.CHg.OH, are alcohols. They are 
derived from the open chain series, by substituting an 
— OH group for an H. Having in mind the chain, the 
.OH may be substituted in the first or last CH3 group 
in the chain, or in one of the middle CH2 groups. 
When in the former it will have the group CH2.OH. 
When in the CH2, the group CH.OH. The first- would 
be a primary alcohol (characteristic group CH2OH) ; 
the latter a secondary alcohol, (characteristic group 
CH.OH). Example, Primary Alcohol: CH3.CH2.- 
CH2.CH2.OH. Secondary Alcohol: CH3.CH.OH.- 
CH2.CH3. 

Products of Primary Alcohols. 

When primary alcohol, CHg.CHgOH, is exposed to 
the air under certain conditions is loses the H2 of the 
primary alcohol group, leaving, in this instance, 
CH3.C.OH;, an aldehyde, having the characteristic 
group .C.OH. The aldehyde then absorbs one O for 
the two H lost, and becomes an acid, CH3CO.OH, the 
characteristic group CO. OH being called the Carhoxyl 
group. Only the H linked in the Carboxyl group is 
replaceable by a base to form a salt. 

'''Atomic" Alcohols. 

When in a compound of the methane (open chain) 
series only one .OH radical is introduced we have a 
monatomic alcohol ; when two or three .OH are in- 
troduced we have a triatomic or diatomic^ alcohol. 



— 55 — 

Alcohols: Methyl Alcohol, CH3.OH (HCH2.OH). 
Ethyl Alcohol, CHg.CH^OH (C^H^.OH). 

Methyl Alcohol is "wood alcohol," a poisonous pro- 
duct. Ethyl Alcohol is "grain alcohol" or the common 
"alcohol," of which there are the absolute (99%), and 
the "alcohol" of 95% strength. The aldehyde of 
Methyl Alcohol is Formaldehyde (40% solution is 
"Formaline"); the acid, formic acid; its salts the 
formates. 

The aldehyde of Ethyl Alcohol is acetaldehyde, 
yielding with CI, "Chloraldehyde." The acid is acetic 
acid, forming the acetates as salts (Potassium, Sodium, 
Ammonium, Zinc acetates are medicinal.) 



Glycerin is a triatomic alcohol, CH2OH.CH.OH.- 
CH2.OH. 

It is a, constituent of fats, forming the base, and 
separated from these by stronger bases (NaOH), 
which in combination with the acid of the fats form 
soaps. The Sodium Soap is a hard soap ; Potassium 
Soap a soft soap ; Calcium Soap and Lead Soap are 
insoluble soaps. 

Uses of Alcohol: Alcohol is a solvent used in phar- 
macy for the purpose of extracting ground drugs. It 
is a solvent for resins, volatile oils and castor oil. 
{Denatured alcohol is alcohol rendered unfit for con- 
sumption by addition of poisonous substances.) It also 
gives rise to other compounds. 

Glycerin is a solvent for certain substances. 



— 56 — 

Ethers. 

Ethers are the oxides of Hydrocarbon radicals. 
Thus (CHg — )20 forms an ether. Two hke hydro- 
carbon radicals linked to oxygen form simple ethers ; 
two unlike hydrocarbon radicals form compound 

ethers, CHg y^ 

CH3.CH2— \J 

The ether of medicinal importance is "Ethyl ether" 
(C2H5 — )20, the ''Ether" of the Pharmacopoeia. 

Ether is a very volatile liquid, boiling at body tem- 
perature. It is very inflammable. Its vapor is heavier 
than air. In medicine it is used as an anaesthetic. 
Ether is prepared from alcohol by the aid of sulphuric 
acid, which, however, forms no part of the finished 
product, though it has given rise to the name "Sul- 
phuric Ether." Ether is a solvent for fats and oils. 



Esters. 

Esters are organic salts. They are formed from 
an alcohol, as a base, replacing the Hydrogen of an 
organic or inorganic acids. The Base is an alcohol 
(primary). It has been show^n how alcohols may be 
so changed that they ultimately produce acids. But 
the primary alcohols themselves are hydrates, and, 
like the inorganic hydrates^ basic. Their radical, for 
example C^H^- — or CHg.CHg. — , can combine with 
an acid to form a salt. The organic salts can be de- 



— 57 — 

composed into Base and Acids, by the application of 
stronger bases, acids, or superheated steam. This 
process of decomposition is called "saponification," 
because the type is the process of making soap (sapo). 

Medicinal Ester^s of Inorganic Acids. 

Ethyl Nitrate, wrongly called nitrous ether, is official 
in the spirit of nitrous ether. It acts in the body, chem- 
ically, like the inorganic nitrites, but more rapidly. 
It is more quickly absorbed, being volatile, and is also 
more quickly eliminated. 

Glyceryl Nitrate is commonly called ''Nitro Glycer- 
in." It is the active ingredient in the spirit of nitro- 
glycerin, or spirit of Glonoin, is rapidly absorbed and 
eliminated. 

Glyceryl nitrate is the chief constituent of Dyna- 
mite. It explodes^ when struck a blow, with great 
violence due to its decomposition. 

Preparations of Nitrogylcerin must be handled and 
stored with great care. 

Esters of Organic Acids. 

These have organic acids and bases. Many of them 
are found in nature, having the nature of oils. If the 
base is Glycerin the oil is fixed; if the salt is formed 
by another organic base the oil is volatile. 

Methyl Salicylate, containing the salicylic acid rad- 
ical, is in nature found as a volatile oil of Wintergreen. 
It serves as one source for the production of salicylic 
acid. The ester is easily saponified. 

Ethyl Acetate is commonly called acetic ether. It 
is not of great medicinal interest. 



— 58 — 

The Fats and Fixed Oils. 

These constitute a large group of organic esters. 
The base is Glycerin, combined with Oleic, Palmitic 
or Stearic acid to form the Glycerin Oleate ("Olein"), 
— Stearate (''Stearin") and — Palmitate. Olein is the 
chief constituent of the oils ; Palmitates and Stearin 
the chief constituents of solid fats. The process of 
saponifying these fats and oils constitutes a large in- 
dustry — soap making. The by-product is always Gly- 
cerin. (See ''Soaps" under Glycerin.) Oils and fats 
are food products. Fat is stored up in the animal 
tissue as reserve food material. 

Adulteration of fats and oils may be done by the 
addition of cheaper oils, or of petroleum products. As 
petroleum cannot be saponified, the degree of saponi- 
fication that an oil is capable of indicates its purity 
("Saponification equivalent"). 

(Fatty oils and fats may contain other acids than 
the above, which have been given as types.) The rep- 
resentative oils and fats are : Olive oil, Cottonseed oil, 
Castor oil. Linseed oil. Lard, Tallow and Butter. 

Miscellaneous Organic Compounds {Open Chain). 

Lactic Acid forms the lactates. Lactic acid is a 
fermentation product formed in sour milk, hence the 
name. 

Oxalic Acid, (poisonous), forms oxalates. 

Tartaric Acid is derived from the crude acid potas- 
sium tartrate, a constituent of grapes, and separating 
from the fermenting juice. The potctssium acid tar- 
tarate is called "Cream Tartar." 



— 59 — 

Tartaric Acid is a dibasic acid. It forms, sometimes, 
double salts, like Potassium and Sodium Tartrate 
(Rochelle Salt). Antimony and Potassium Tartrate 
(Tartar Emetic). 

Citric Acid. It is an acid found in nature chiefly 
as the acid constituent of Citrons (Lemons), hence 
the name. It is a tribasic acid. Its salts are the 
Citrates. (Potassium, Sodium, and Manganesium 
citrate). When absorbed the citrates are completely 
burned (oxidized) in the tissues, to form the carbon- 
ates of the base. 

Oleic Acid. Oleic acid is the acid radical in Olein, 
or fatty oils and fats. Its salts are the oleates. 

Linoleic Acid is the special acid found in Linseed 
oil It differs from Olein chemically, and is the basis 
of the drying oils. 



Amines and Amides. 



An Amine is a chemical compound formed by the 
introduction of an alcohol radical (as CH3. — ) into 
Ammonium by substitution of an H ; thus, CH3.NH2, 
methylamine. 

An Amide is a chemical compound, in which one H, 
(or more) of NH3 have been replaced by an acid 
radical, thus NH2.CH3CO. 

Their chief interest lies in the fact that Amines form 
as decomposition products of albuminous putrifaction. 



— 60 — 

Table Reviewing the Classification of Compounds and 
Derivatives of the Open Chain. 

1. Hydrocarbons. 

II. Derivatives: a) CHClgjCHIg, (substitution), 
b) The hydrates of hydrocarbon radicals (alcohols) 
primary — CH2OH, and secondary ( — CH.OH). c) 
The oxides of hydrocarbon radicals, ethers. 

III. Oxydation products of primary alcohols: Al- 
dehydes — , Acids. 

IV. Esters. (Salts.) Organic bases with organic 
or inorganic acids. 

V. Amines and Amides. 



The Carbohydrates. 



These organic compounds were originally so desig- 
nated because the molecule was found to consist of 
Carbon with Hydrogen and Oxygen, the latter two 
elements present in proportion of H2O, as in water, 
hence the name, "Carbohydrates." 

It has now been determined that they are oxydation 
products (aldehydes and ketones) of alcohols. The 
carbohydrates are important food products. The class 
includes, as typical representatives. Starch and Sugar. 

Starch. The formula of starch is CgH^^Og. Starch 
is an important constituent of many foodstuffs : Pota- 
toes, Rice^ Grain. Starch is closely related to Sugar, 
the simplest sugar, Grape Sugar or Glucose, having 
the formula C^Yi-^^O^, that is, the formula of Starch 



— 61 — 

plus H2O. Starch can be made to take up this water 
molecule and become sugar, by imply boiling it with a 
dilute mineral acid. This process is called "hydration," 
or ''inversion" of the starch. Ferments (see) accom- 
plish the same change. 

Cane Sugar has the formula C^2^22^ir ^^ ^^ ^^^ 
formula of Glucose twice, minus one H2O. Cane 
sugar can, like starch, be hydrated or inverted to be- 
come Grape Sugar or Glucose (Cq'H.^^Oq)^' Starches 
or sugar, as food, becomes converted into grape sugar 
before absorption. (See Digestion.) 

Cellulose belongs also to the group of Carbohydrates. 
It is a constituent of vegetable tissue. Chemically, its 
interest lies in the fact that cellulose can be made to 
form compounds with the nitric acid radical, the cellu- 
lose nitrate^ or "Nitrocellulose." It is a highly explo- 
sive substance, called "Gun Cotton." Dissolved in 
ether, cellulose nitrated to a lesser degree and non- 
explose, forms Cellodion. Upon evaporation of the 
ether a film of the cellulose nitrate is left behind. 



— 62 — 

II 

The Closed Chain Hydrocarbons. 

Referring to the illustration of the formation of a 
closed chain hydrocarbon, we have seen that six C 
atoms are linked together to form the simplest mole- 
cule. If the linking between these six C atoms is by a 
single link, the hydrogen compound of the six C atoms 
has the formula CgHj2- ^^ every alternate C is united 
by double links the compound has the formula CgH^. 
This is, in fact, the simplest compound known in prac- 
tice. We take it as our basis for the derivatives. The 
derivatives may be obtained firstly, by substitution or 
addition within the molecule (or nucleus) C^Hg. When 
the substitution has taken place by a radical, further 
changes in the new compound may be made by further 
substitution or addition within the nucleus, or by sub- 
stitution within the side group (or chain). 

The compounds and derivatives of CgHg are also 
called "the Aromatic Hydrocarbons." 



Derivatives by Substitution within the Nucleus. 

The compound is CgH^, Benzene, or Benzol, (not 
Benzine). Its simplest radical is CgH^ — called Benzyl. 
This may link on to any other radical, organic or in- 
organic^ to form new compounds. For our purpose, 
the first compound of importance is CgH5.NH2. This 
compound is best called Phenylamine (secAmines), 
because the radical is, for reasons to be stated, also 
called Phenyl. This compound is the basis of the 
various anilines (dyes) and is commonly called aniline. 



— 63 — 

Acetanilid: When one of the H in the Amine group 
NH2 in AniHne (CgHgNHg) is replaced by the acetic 
acid radical, CH3CO, we obtain the compound "Acet- 
anilid" QH^.NH.CHgCO. 

Many other compounds are related to, or are pre- 
pared from, aniline; they are the so-called Coal Tar 
products. 



Phenols. 

Phenols, as a class, are the nucleus substitution hy- 
drates of the closed-chain hydrocarbons. They are 
not alcohols. 

CgHg.OH is Phenol of the Pharmacopoea. It dis- 
plays, under certain conditions, weak acid properties, 
though not chemically an acid. It was therefore, called 
^'Carbolic Acid." Carbolic Acid or Phenol is a crystal- 
line solid, soluble in 5^ and 95, parts of water, and in 
any amount in glycerine. It forms weak salts, the 
carbolates. Phenol is derived, as a rule, from coal 
tar. 

Other compounds belonging to the Phenols : 

Crude Carbolic Acid, or Crude Phenol, contains sev- 
eral other related constituents, which are removed by 
purification. They are, however, valuable as disinfec- 
tants, like Phenol itself. 

Thymol is a Phenol derived from oil Thyme, chiefly. 
Its Iodine compound is ''Aristol." 

Creosote, a product formed by the destructive dis- 
tillation of wood (Beechwood). *'Coal Tar Creosote" 
is usually contaminated with carbolic acid. 



— 64 — 

Aromatic Alcohols, Aldehydes and Acids. 

Aromatic Alcohols are the hydrates of hydrocarbon 
radicals of the side groups. 

They are formed in this manner : 

CgHg.CHg; C3H5.CH2OH. This is Benzyl Alcohol. 
The primary aromatic alcohols yield, upon oxidation, 
the corresponding aldehyde and acid. 

Thus, CgHg.CH^.OH is Benzyl Alcohol ; CgH^COH, 
Benzaldehyde ; CgH^.COOH, Benzoic Acid. 

Benzaldehyde is a constituent of the volatile oil of 
bitter almonds. Upon exposure of the oil to the air. 
Benzoic acid crystals separate. 

Benzoic acid is usually made by synthesis, but it 
may be found naturally in Gum Benzoin, hence its 
name. 



Phenol Alcohols. 



It may easily be conceived, how a Phenol and an 
aromatic alcohol may be formed from the same nu- 
cleus, thus: CgHg, Benzene; CgH^ — , nucleus radical 
Benzyl; CgH^.CH^OH, Benzyl alcohol; CgH^.O//.- 
CHg.OH, a Phenol alcohol, having the character of a 
Phenol and of an aromatic alcohol. This Phenol rad- 
ical does not change the oxydation products of the 
aromatic alcohol that have been enumerated, but the 
acids are distinguished as Phenol acids. Thus, 
CgH^.OH.CH^OH yields C,H,.OH.CO.OH, differing 
from Benzoic acid in having the additional OH in the 
nucleus, instead of (the replaced) H; or, it contains 



— 65 — 

one O more than the Benzoic acid ; it is called, there- 
fore, O^fj/benzoic acid, or specifically, Salicylic acid. 

Salts. 

Benzoic acid forms Benzoates (of Na., NH3.) 
Salicylic Acid has been prepared from various com- 
pounds found in nature. It occurs chiefly in Oil of 
Wintergreen, as the methyl salicylate, an ester. It is 
prepared on a large scale synthetically. The salts of 
salicylic acid are the Salicylates (Na). 



To the phenol acids belong also, Gallic and Tannic 
acid, constituents of many plants. Vegetable prepara- 
tions, containing Tannic acid, are incompatible with 
solutions of Iron Salts. 



Carbon Compounds of More than One Nucleus, 

One or more nuclei of the formula CgHg may link 
together to form new compounds, giving rise to new 
derivatives. The chemistry of such compounds is be- 
yond the scope of the present study. Many of these 
compounds have practical interest from a medical 
standpoint. Others possess chiefly a technical interest. 
Those of medicinal interest will be mentioned. 



— 66 — 
The Derivatives of Vegetable Drugs. 

While the study of drugs is part of the study of 
materia medica, some constituents of drugs possess 
definite chemical interest. Some of them are related 
to the compounds just considered. Constituents of 
special interest are 

Alkaloids; the word Alkaloid signifies ''like an 
alkali." They are organic, usually crystalline, sub- 
tances, the products of vegetable life, which have basic 
properties ; with acids they form salts. Chemically 
they belong to derivatives of the closed chain hydro- 
carbons, but contain N in the nucleus. 

The free alkaloids are, as a rule, insoluble in water, 
but soluble in Alcohol, and some in Chloroform and 
Ether. Their salts are most soluble in water. The 
alkaloids can be liberated from their salts by stronger 
bases. There are some insoluble salts of alkaloids^ the 
Tannates, Iodides and Bromides. (Incompatibility!) 

Alkaloids are usually the active principles of the 
drug from which they are obtained. Many are quite 
potent and toxic. Their English names terminate in 
ine; their Latin names in ina. (Example of alkaloids: 
Morphine, Quinine, Strychnine.) 

Cadaveric Alkaloids. When albuminous tissues de- 
compose there are formed certain substances which 
are extremely poisonous, and have the character of 
alkaloids. They are called Ptomaines. When con- 
sumed with decomposed albuminous food, they may 
cause poisoning. (Example, in cheese, sausage). 



— 67 — 

Glucosidcs are constituents, and sometimes the active 
principles, of plants. As the name indicates, they are 
related to Glucose. When boiled in aqueous solution 
with a diluted mineral acid, they will be changed to 
Glucose and some other substances. Glucosides do not 
include so many potent substances as the alkaloids. 
Glucosides are soluble in water. (Example, Digitalin.) 
The designation of Glucosides has been fixed; their 
English names terminate in in; their Latin names in 
inum. — 

Other plant constituents are: The neutral or hitter 
principles, the chemistry of which is not well under- 
stood. ( Example A loin ) . — 

The physical properties of Gum and Resins must be 
noted: Gums are soluble in water; insoluble in alco- 
hol. (Example: Gum Arabic, Acacia.) Resins are 
soluble in alcohol, insoluble in water. 

The Extraction of Drugs. 

Drugs are extracted in order to obtain pharmaceuti- 
cal preparations representing the virtue of the drug, 
in the form of the active constituents, more or less 
pure ; these active principles may be completely isolated 
(Alkaloids, Glucosides) or be dissolved in the extract- 
ing fluid or extract. The extracting fluid is called the 
menstruum. It is required that the drug must be in a 
proper state of division for purpose of extraction. The 
menstruum is selected according to the nature of the 
active constituents to be extracted. An alcoholic, or 
hydro-alcoholic menstrum is usually chosen, because 
it has good solvent qualities as well as good keeping 



— 68 — 

qualities. Among the classes of pharmaceutical prepar- 
ations are Infusions, Decoctions, Tinctures, Fluid Ex- 
tracts and Extracts. 



Fermentation. 



Fermentation is the decomposition of an organic 
compound through the action of a ferment. The fer- 
ments are substances that seem to act through mere 
contact with the substances undergoing fermentation. 
The ferment does not undergo any changes during the 
process. 

Ferments are classified as organized and unorgan- 
ised. The organized ferments are : yeast plants, bac- 
teria or bacilli, and molds ; the unorganized ferments 
are chemical products of cells of the body, or of plants. 
They further differ in that the organized ferments are 
inhibited, or killed, by the use of the common antisep- 
tics ; the unorganized ferments are not influenced there- 
by. The unorganized ferments are also called "Enzy- 
mes." All ferments are destroyed when subjected to a 
boiling water temperature. 

The chemical changes accomplished by fermentation 
consist of hydration of the substances, or in oxydation 
(especially within the tissues.) 

Putrifaction is the decomposition of albuminous 
material through anaerobic bacteria. 

The organised ferments are chiefly represented, a) 
by the various yeast plants, which bring about alcoholic 



— 69 — 

fermentation in solution of sugar. (Wine and Beer 
are common products ; likewise Whisky, Brandy, and 
pure Alcohol.) 

b) The bacteria, including the ''Bacillus Acidi Lac- 
tici," producing the lactic acid fermentation ; the "bac- 
terium aceti" and other bacteria producing the acetic 
acid fermentation from alcoholic solutions. The latter 
oxidize the alcohol to acetic acid, and are found as the 
''mother of vinegar" in old ciders, etc. — 

The unorganised ferments include many well known 
substances. Their names, as ferments, terminate in 
— ase, but this designation is not always employed. 

Unorganized Ferments, or Enzymes, are: Ptyalin, 
in the Saliva, Diastase in Grain, Invertin in Yeast, 
Amylop^sin in Pancreatic Secretion changing Starch 
and Grape Sugar into Glucose. Pepsin and Trypsin, 
changing albumins into albumoses and peptones. 
Steapsin, splitting fats, Enterokinase^ in the intestines 
changing trypsinogen into trypsin. 



The Chemistry of Proteids. 

Proteids are organic nitrogenous compounds, con- 
taining, usually, the Element C, H^ N, O, S and P. 
The molecule is of exceedingly complex composition. 
It has never been possible to construct, by artificial 
means, a molecule of proteid matter. 

Proteids make up the contents of animal (and vege- 
table) tissue cells. A simple representative of proteids 



70 



is "Albumen" or Egg-white. Proteid matter is also 
called albuminous matter. 

Physical properties of Proteids: They are soluble 
in water, or in a solution of Sodium Chloride, but in- 
soluble in alcohol or ether, and they may be precipi- 
tated from their solution by certain neutral salts (as 
Magnesium Sulphate.) They are colloid substances. 

By the action of acids and alkalies Proteids may be 
decomposed ; by the action of digestive ferments, they 
are split up into simpler compounds, thus through the 
action of Pepsin and Trypsin into Peptones. Their 
ultimate decomposition products may have a very sim- 
ple molecular composition, and some are crystalline. 
An attempt has been made to build up from these ulti- 
mate decomposition products, the more complex com- 
pounds, with only a limited success so far. 

Classification of Proteids. 

Proteids may be divided into: 

1. Albuminoids, including Albumen, Grlobuline and 
derivatives, Acid-Albumens, Alkali-Albumens, Album- 
oses and Peptones. 

2. The Nucleo Albumens. 

3. Proteids proper: Glucoproteids and Chromopro- 
teids. 

4. Gelatinoids. 

Albuminoids. 

The albumins include Blood — or Serum Albumen, 
Egg Albumen, and Milk (Lact) Albumen. These 
albumins are soluble in water, and with acids and alka- 
lies they form the corresponding compounds. The 



— 71 — 

solution of albumin in water, in the presence of neutral 
salts, is disturbed by the application of heat — the albu- 
men is "coagulated." They may also be precipitated 
through certain substances, such as Nitric Acid, Picric 
Acid, Trichloracetic Acid, and Potassium Ferrocyan- 
ide. 

Globulins are insoluble in water^ but soluble in dilute 
NaCl solution. They include Vitellin, from the Yolk of 
of Egg, Fibrinogen and Serum Globulin. The remain- 
ing members of the group are derivatives of the pro- 
teids, as mentioned. 

The Nucleoalbumins. 

These contain Phosphorous and sometimes Iron. 
They include Casein from Milk. 

The Proteids Proper. 

The molecule of these compounds consists of part 
albuminoid, and part carbohydrate of other compounds. 
This is of 6ome importance in the Glucoproteids. One 
cannot deprive food entirely of Carbohydrates by feed- 
ing proteids, for carbohydrates may be derived from 
certain Proteid compounds. 

The Chromoproteids consist of protein with a color- 
ing matter. The most important member of this group 
is Haemoglobin, the iron containing coloring matter of 
the red blood corpuscles. The coloring matter contain- 
ing the iron is called Haematin. When the combina- 
tion with oxygen is established, the resulting compound 
is Oxyhaemoglobin ; when the Oxygen has been given 
ofif reduced haemoglobin is formed. These are the suc- 
cessive changes that go on in the circulation. 



— 12 — 

The Chemistry of Foods and Digestion. 

Foods may be divided into Starches or Carbohy- 
drates, Proteids and Fats. These must be associated 
with inorganic salts and water. 

The purpose of taking food is to replace waste pro- 
ducts of the body, to supply a source for energy, and 
to build up tissue. The food is taken, digested, ab- 
sorbed and assimilated. It may be used up in the body, 
or remain stored up within the tissue. In general it 
may be stated that Carbohydrates and Fats supply 
energy for muscular work. The Proteids replace waste 
within the cells. The waste, or the resulting decompo- 
sition products, are excreted chiefly by means of the 
kidneys and lungs, also through the skin and gastro 
intestinal tract. 

Digestion. 

The purpose of digestion is to so simplify the food 
molecules that they may be absorbed. The Carbohy- 
drates are digested partly in the mouth, the Proteids in 
the stomach, and the Fats within the intestines through 
the intestinal and pancreatic secretions. In some ani- 
mals the digestive organs are differently arranged, but 
the chemical process is the same. 

Carbohydrates. 

Carbohydrates are inverted within the mouth, 
through the action of the Ptyalin (ferment) in the 
saliva, to sugar. If the inversion is not completed 
through the saliva, it is completed through the ferment 
Amylopsin from the pancreas, when the food reaches 



— 73 — 

the intestines. The fluids in which PtyaHn and Amy- 
lopsin act, must be alkaHne. All Carbohydrates are 
absorbed as Grape Sugar. {See Chemistry of Carbo- 
hydrates.) 

Proteids. 

They are digested within the stomach. The stomach 
secretes a ferment called Pepsinogen; it is a type of a 
/^ro-enzyme, to form the enzyme proper. The stomach 
also secretes a fluid acid with HCl. This acid changes 
the pro-enzyme pepsinogen to pepsin. 

The proteid food is first changed by the acid to acid- 
albumen; after this the pepsin digests the albuminous 
food to albumoses, and ultimately to peptones. 

The digestion of all food is not completed within the 
stomach. The partly digested food is propelled into the 
intestines where the process is completed. 

Intestinal Dige^stion. 

In man and in some animals the intestines form the 
chief organs of digestion. The digesting fluids within 
the intestines are the juices of the intestines ("succus 
entericus"), the secretion of the pancreas, containing 
Trypsin, Amylopsin, and Steapsin, assisted by the bile. 

The Carbohydrates are finally inverted to Grape 
Sugar through the Amylopsin; the Proteids through 
Trypsin to Peptones^ and the Fats, being first ennulsi- 
fied through the alkaline solutions within the intestines 
are, perhaps, partly decomposed through the Steapsin. 

After the digested food has been absorbed, the undi- 
gested and indigestible food passes through the intes- 
tinal canal and is excreted. It has ktely been claimed, 



— 74 — 

that the cellulose which constitutes a great part of the 
foods of many animals, is decomposed within the intes- 
tines through a ferment residing within the cellulose. 

Assimilation and Excretion. 

The Carbohydrates, or Sugar, absorbed are stored 
up (and used), as Glycogen within the liver. So much 
of the nitrogenous food as is needed to replace waste 
becomes a constituent of the tissue cells. The Fats are 
either "burned" or stored up as fat within the tissues. 
(It is possible that fat may also be formed from the 
other foods.) 

A body may increase in weight, Urst, by an increase 
in the amount of tissue; second, by an accumulation 
of fat within the tissue. 

The inorganic salts of food consist chiefly of Sodium 
Chloride, of the phosphates, and sulphates. They are 
needed to hold the proteid matter in solution within the 
blood, and to supply some of the constituents of the 
secretions. The water is needed to dissolve the digested 
food, and to dissolve, for purpose of elimination, the 
waste products of the tissues. It is needed to maintain 
the balance of fluids in the tissue to replace the excreted 
water. 

All changes involved in the process of metabolism 
are carried on by ferments within the tissue cells. 

Decomposition Products. 

Through the burning of Carbohydrates in the tissues 
there are produced CO2 and HgO, the former excreted 
through the lung. The fats give rise to similar decom- 
position products. 



— 75 — 

The decomposition of the Proteids within the tissue 
gives rise to many products, which go through a great 
many changes within the tissues, chiefly within the 
liver, until they are finally excreted as Urea, or Uric 
Acid. Urea is the chief product of Proteid decompo- 
sition in man. In some animals (birds) Uric Acid 
seems to take its place. Some of the intermediate pro- 
ducts between Proteid and Urea are the Xanthin bases. 

These decomposition products, dissolved in water, 
are excreted in the Urine. 



The Chemistry of the Urine. 

The Urine consists of : 

a) the solids in solution: Urea and Uric Acid and 
other nitrogenous decomposition products ; the inor- 
ganic salts: the phosphates, chlorides and sulphates of 
Potassium^ Sodium, Calcium, Magnesium and Am- 
monium. 

b) the water holding these substances in solution. 

The percentage composition of the Urine varies 
with the Urine of different animals, and with other 
circumstances. Thus a large amount of water con- 
sumed and excreted dilutes the Urine. — The nitro- 
genous constituents are the decomposition products of 
cell metabolism, and of food consumed. 

The inorganic constituents are partly derived from 
nitrogenous matter, (sulphates and phosphates), but 
mostly from the mineral constituents of food. 



— 16 — 

The Urine Under Pathological Conditions. 

Under pathological conditions, the Urine may differ 
from the normal : 

1) The Urine as a whole may be suppressed. 

2) There may be want of excretion of the solid con- 
stituents of the Urine. 

3) There may be abnormal constituents of the Urine, 
such as albumen, sugar, pus, blood, and indican. 

4) There may be an increase in the quantity of cer- 
tain solid constituents of the Urine, denoting greater 
waste. 

The Clinical Examination of Urine. 

The object of the Clinical Examination of the Urine 
is to detect certain changes from the normal as an aid 
to diagnosis. 

In veterinary medicine the practical application of 
the urine analysis is still quite undeveloped, but, like in 
medicine in general, it will, doubtless, become of 
greater importance. The clinical methods of examin- 
ation are, therefore, described. 

1) Physical Examination. The quantity of 24 hours 
is measured. The Urine is inspected as to color, odor, 
and the presence or absence of sediment. The specific 
gravity is taken and compared with the normal: In- 
crease of solids increases sp. gr., and dilution decreases 
it. 

2) The specimen is then filtered. 

3) Chemical Examination: 

Reaction with litmus paper, acid or alkaline. The 
reaction of the Urine may depend largely upon the 



— 77 — 

character of the food ; an acid or alkaHne reaction may, 
therefore, be normal. 

The total solids may be estimated from the specific 
gravity ; or they may be determined by evaporating 10 
grams of the Urine to dryness upon the water bath. 

The Calcium salts may be determined by igniting the 
residue after evaporation, extracting with diluted HCl, 
neutralizing the excess of HCl, and precipitating the 
Calcium with Ammonium Oxalate^ drying and weigh- 
ing the residue. (It has been suggested, that in Osteo- 
porosis there is an absorbtion and excessive elimination 
of the Calcium from the bone tissue, and that the analy- 
sis of the Urine may lead to an early differential diag- 
nosis. 

Albumen may be most readily detected by coagulat- 
ing the same by boiling, or by the addition of nitric 
or acetic acid. 

The albumen may also be precipitated by the addition 
of picric acid, trichloracetic acid, or potassium ferro- 
cyanide. 

Sugar may be detected by boiling the specimen with 
Fehling's Solution (alkaline cupric tartrate solution.) 
If sugar is present, a precipitate of reduced Copper Ox- 
ide is formed. 

Indie an. It is believed that indican in the Urine is a 
sign of excessive albuminous putrifaction in the intes- 
tines. On the other hand a varying amount may be 
found as a normal constituent of Urine. It may be 
detected by heating the Urine with an acid (HCl) con- 
taining an oxidizing agent (Ferric Chloride) : a blue 
color indicates the presence of Indican. 



— 78 — 

Pus in Urine is detected by the microscope. 

Blood Cells may likewise be detected with the micros- 
cope. 

Blood Coloring Matter may be detected chemically 
by adding to the Urine H2O2, and a freshly prepared 
tincture of guaiac: a blue color indicates haematin. 
Under the same circumstances a tincture of aloin gives 
a cherry-red color. 



— 79 — 

The Chemistry of Milk. 

The Character of Milk. Milk is a fluid composed of 
water and substances suspended or dissolved therein. 
Pure milk may be white or yellow-white in color, and 
possesses a more or less ''rich" taste, faintly sweet. 
Upon standing, milk will separate into an upper layer 
("Cream") and a lower layer. 

Whole milk contains from 12 — 16 per cent of solid 
matter, ''total solids ;" the balance is water. The "total 
solids" are composed of from 3 — 5 per cent of fat ; the 
balance is casein, the proteid of milk^ with a smaller 
amount of milk-sugar, and inorganic salts. 

The fat is sometimes called "butterfat;" it is com- 
posed of glycerine with various fatty acids, and is sus- 
pended in fine globules surrounded by the albuminous 
constituents of the milk. Some herds of cows produce 
a milk very rich in fat (Jerseys) ; other herds produce 
less fat (Holsteins). A milk may be rich in fat and not 
possess the "rich" yellow-white color. 

Cream consists of the butterfat of the milk plus 
casein. It rises to the surface upon standing, or may 
be separated through centrifugal force. The former is 
called gravity cream, and contains usually about 23 to 
25 per cent of fat, depending upon the character of the 
milk. The centrifugal cream may contain from 8 — 46 
per cent of fat. 

Butter is formed when, by means of churning, the 
fat is entirely liberated fromi the enclosing proteid mat- 
ter. 

Skimmed Milk is the milk deprived of its cream. It 
still contains some nutritious material of lact albumen, 



— 80 — 

milk-sugar, a small amount of residuary fat and casein. 
It is more or less bluish in color and transparent or 
translucent. 

Casein is held in solution in the milk through its com- 
bination with calcium phosphate. When this compound 
in the milk is broken up by the addition of an acid, the 
casein precipitates as curds. It may likewise be precipi- 
tated through the milk curdling ferment rennin, but 
this precipitate is not deprived of its calcium salts. 

The Fat and Casein, with the milk-sugar^ constitute 
the chief nutritive substances of the milk. 

Milk forms one of the most important food products. 
It is especially desirable and necessary that the milk be 
pure. 

The Bacterial Contents of Milk. 

Milk is a sterile fluid, but there are so many sources 
of contamination that it is never produced as a sterile 
fluid. A very good grade of milk will contain some 
10,000 bacteria to the cubic centimeter ; the worst milk 
on the market may contain 5,000,000 bacteria to the 
cubic centimeter. These bacteria may or may not be 
pathogenic. (They may include the bacilli of tubercu- 
losis from tuberculous cattle.) 

The bacterial contents of milk may be killed to some 
extent by heating the milk, that is Pasteurizing or Ster- 
ilizing the milk. But the milk loses it value as a food 
to some extent through this process. At any rate, the 
effort must be to produce pure milk, and not to hide the 
dirt in milk. 



— 81 — 

The Production of Pure Milk. 

Pure milk is milk sufficiently rich in constituents 
(solids) to meet the requirements provided, and suffici- 
ently clean that its bacterial contents does not exceed 
the established limits. Different states and communi- 
ties have fixed different standards of fat contents, and 
total solids. The average is perhaps 12.00 per cent 
total solids, and 3% of fat. The regulation of the bac- 
terial contents has not been so thoroughly established. 
Requirements for the Production of Pure Milk. 

The Cows of the herd must be free from constitu- 
tional and local disease (Tuberculosis!) All cattle 
should be tested by the tuberculin method for tubercu- 
losis, and infected cattle at once excluded. 

The Food for the Cows must be suitable and suffi- 
cient ; the feeding of ''wet slop" from breweries, con- 
taining fermentation products, must be excluded. The 
dried residue of brewery slop may be permitted. All 
cattle must be allowed sufficient exercise in the open 
air, and sufficient pasture in season. 

Milk-producing cows should be stabled under condi- 
tions of absolute cleanliness. The nearer conditions of 
milking approach surgical cleanliness, the less danger 
there will be of contamination of the milk. 

The milk should be promptly cooled, and delivered 
with a temperature not exceeding 50° F. 

Adulterants in Milk. 

The adulterants may be: a) Water, to dilute the 
milk ; b) the cream may be removed by skimming. 



— 82 — 

Milk so treated is ''thin," sometimes bluish ; c) Coloring 
matter may be added to give whole milk a desired 
''rich" yellowish color, or to cover evidence of diluting 
or skimming; d) Preservatives may be added such as 
Formaldehyde or Boric Acid. 

Examination of Milk. 

In order to establish the character of milk it must be 
examined bacteriologically and chemically. The bac- 
teriological examination is made by making cultures of 
the milk upon plates, and counting the colonies. 

The Chemical Examination: 

a) Physical Inspection : The presence or absence of 
a sediment is noted ; the color and odor of the milk, and 
its taste ; the separation of cream. 

To separate sediment : Dilute the milk with water ; 
close the neck of percolator with a cork; fill the 
percolator with milk, allow the sediment to seperate in 
the neck. Draw off (siphon) the clear supernatant 
milk ; dilute the balance with water, allow to stand, and 
repeat dilutions until all sediment has separated. The 
sediment may then be further examined. 

b) Chemical Analysts: 

The specific gravity of the milk is depending upon 
the fat and upon the "solids not fat" in the milk. It 
alone is not an absolute indication of the value of the 
milk. 

The acidity in milk is caused by carbonic acid and 
acid phosphates of the milk, when quite fresh. In older 
milk the acidity is increased by fermentation lactic acid. 



— 83 — 

In fresh milk of the best quaUty the total acidity does 
not exceed 0.2% as lactic acid. 

The chief reliance in chemical analysis must be 
placed upon the estimation of total solids, and fats. 

Total solids are estimated by drying 5 grams of milk 
upon the water bath to constant weight. The differ- 
ence in weight is the water; the residue the ''total 
solids." 

The fats are estimated by separating them from the 
milk as follows : 20 grams of milk are mixed with 20 
grams of pure (U.S. P.) HCl in a flask, and heated 
upon a water bath until a chocolate-brown color is pro- 
duced — i. e. until the organic matter is destroyed. The 
contents are cooled, and 20 grams of ether are added 
to the flask, agitated during 10 minutes, the ether al- 
lowed to separate, and poured off into a clean weighed 
flask. The ether extraction is repeated 2 or 3 times 
with 10c. c. of ether; the ether extracts are mixed, the 
ether evaporated or distilled off^ the residue dried at 
water bath temperature, and weighed, and calculated 
to 100 grams. 

The "Solids not Fat," are the total solids minus the 
fat.— 

Formaldehyde is detected by boiling 1 part of milk 
with 4 parts of pure HCl, containing a trace of Ferric 
Chloride ; a violet color indicates Formaldehyde. 

Boric Acid is detected by taking 1 drop of the milk, 
2 drops of HCl^ and 2 drops of Tumeric Tincture, mix- 
ing them in an evaporating dish, and drying upon a 
water bath, and add to the residue one drop of Am- 
monia Water. Boric Acid or Borax produces a bluish 
green color. 



— 84 — 

Coloring Matter may be readily detected by precipi- 
tating the casein in milk with rennin. If artificial col- 
oring matter has been added the curds of casein will be 
colored. 

Modified Preparation of Milk. 

Condensed Milk is whole milk evaporated in a vac- 
cuum ; the residue may or may not contain added sugar 
as a preservative. 

Modified Milk is milk in which the relative propor- 
tions of cream and proteids have been altered by the 
separation, or addition of cream. It meets to some 
extent the demands of infant feeding. 



— 85 — 

The Chemical Analysis of Meat and 
Food Products. 

Meat and food products may be analyzed for the pur- 
pose of determining their constituents of food value, 
or of detecting adulteration. 

Food products may be adulterated for the purpose of 
preservation, or to increase bulk, or for other reasons. 

The methods of analysis depend upon the physical 
character of the material, upon its chemical composi- 
tion, and upon the substance tested for. Certain gen- 
eral rules may be laid down as applying to the analysis 
of food stuffs in general. 

The detection of foreign constituents in foods gen- 
erally necessitates their isolation in sufficiently pure 
form to be identified by certain tests. 

Taking meats or other solid food as the type, the dif- 
ferent steps are as follows : 

1. Comminution of the material, by cutting or grind- 
ing. 

2. Separation of adulterants by : 

a) Extracting with a suitable solvent, or 

b) Charring and extracting the residue, or 

c) Igniting and extracting the ash. 

2 a) Extracting with Suitable Solvents. A con- 
venient quantity, say 50 grams, may be taken. Put into 
a flask, dish or beaker, the solvent is poured upon it, 
and it is allowed to macerate or digest for a sufficient 
length of time. It is then filtered, and the filtrate in- 
vestigated. 



— 86 — 

The Choice of Solvent depends : a) Upon the nature 
of the substance to be extracted, and b) Upon the 
nature of the material under investigation. 

a) It is required to be a good solvent for the sub- 
stance to be extracted ; thus one may choose water ( hot 
or cold) acid or alkaline; Alcohol, Ether. 

b) Such a solvent should be selected, where there is 
a choice, that will dissolve least of other undesirable 
substances from the material. 

The nitrate may be tested, if sufficiently pure, for cer- 
tain constituents directly, or these may be separated by 
chemical and physical, means ; thus, an immiscible 
liquid may be shaken with the solution that certain sub- 
stances, if present, may pass into this second liquid. 
(See Salicylic Acid.) 

2 b) Charring and Extracting the Residue. ''Char- 
ring" is the carbonizing of the material by burning it 
to blackness. Its purpose is to destroy certain inter- 
fering constituents of the material, so that the adulter- 
ant may be more easily extracted. It is not applicable 
where the suspected adulterant would also be destroyed 
by heat (organic substances), but only applicable where 
inorganic and nonvolatile substances are tested for. 

2 c) Igniting and Extracting the Ash. The object 
of the process of ignition is to destroy all organic mat- 
ter, and examine the ash. It is only applicable to in- 
organic nonvolatile substances. 

Special Method: When volatile substances are pres- 
ent, such as sulphurous acid, they may be directly 
separated by subjecting the Extractive from 2 a) to 
simple distillation. 



— 87 — 

The Analysis of Fluid Foods. 

Fluid foods may be subjected to direct distillation 
for volatile adulterants, or shaken out with an immis- 
cible solvent (as for salicylic acid), or they may be 
treated as solid foods, and charred or ignited. 

It must be clearly understood that the above are 
general methods. The character of the food and of the 
adulterant may be such that the ordinary methods are 
not applicable, and all the resources of the analyst may 
be taxed for the devising of suitable processes, but for 
these, special works must be consulted, such as Leach, 
on Food Analysis, or others. They are usually only 
acquired through long laboratory experience. 

Special Processes.* 

The Examination of Meats for the More Common 
Adulterants. 

Salicylic Acid, Boric Acid, and Sulphurous Acid are, 
perhaps, the most frequently employed preservatives 
in meat; the direct methods employed for the detec- 
tion of these adulterants are as follows : 

For Salicylic Acid. The meat is extracted directly 
with ether; the ether is poured off {decanted) , evap- 
orated, a few drops of hot water added to the residue, 
and a drop of the solution of Ferric Chloride added; 
if salicylic acid is present, a violet color is produced. 

Note: The fatty parts of the sample interfere by 
dissolving in the ether, and these must be removed by 

* (Leach, Food Inspection and Analysis, tias been extensively 
consulted.) 



— 88 — 

mechanical means prior to extraction. If Salicylates 
are present, the watery extractive must be made acid 
by a few drops of sulphuric or hydrochloric acid, and 
then shaken out with ether. 

Boric Acid, either free or as borates, is detected by 
adding sufficient water to the meat to rub it into a thin 
pasty mass ; this soluiton is made acid by HCl, and 
digested for ^ hour. Filter paper saturated with Tur- 
meric Tincture is then dipped into the solution ; a red 
coloration of the paper, turned a blue-gray by ammonia, 
denotes boric acid. 

Sulphurous Acid may be present^ free or as Calcium 
Bisulphite. It is not infrequently found in minced 
meat. 

Detection: Take 25 grams of meat, mix well with 
100. CC of water, and acidify with phosphoric acid. 
Distil this mixture and treat the distillate with bromine 
water, or bromine, to oxidize the sulphurous acid to 
sulphuric acid, and add a solution of BaCl2 ; a precipi- 
tate of BaSO^ denotes the presence of sulphides in 
the sample. 

Note: The odor of the sample may suggest the 
presence of TIgSOg. 

Saltpetre, or KNO3, is frequently employed in meat 
preparations to preserve the natural color. It may be 
detected by adding to the finely divided material a 1% 
solution of diphenylamine in HgSO^ ; nitrates produce 
a blue color. 

Starch-containing Material may be detected by ex- 
tracting the material with water, and adding a drop of 
Solution of Iodine (LugoFs Solution) ; a blue color 
denotes Iodine. 



— 89 — 

Glycogen is a constituent chiefly of horse flesh. It 
may be detected by extracting the material with water, 
and adding a few drops of Lugol's Solution of Iodine ; 
a wine color indicates Glycogen. It disappears upon 
heating, and appears again upon cooling. 



The Analysis of Fats and Oils (Edible.) 
Butter. 

For the present purpose, any butter other than the 
fresh butter, uncontaminated, is called adulterated. 

Adulterated butter may consist of ''Renovated But- 
ter/' or admixture with oleomargerine ; or it may con- 
tain coloring matter, or preservatives. 

Renovated Butter is butter which has become rancid, 
and which has been so treated as to remove the evidence 
of rancidity by "aeration" and other processes. 

Detection: The simplest test is the foam test (cited 
in Leach, Food Analysis) ; a teaspoonful of the butter 
is melted in a spoon under constant stirring, over a 
low bunsen flame; fresh butter boils quietly with the 
production of a rich foam. Renovated butter (and 
oleomargerine, also), boils with much sputtering, with- 
out foam. Oleomargerine may be detected by the above 
test. The odor of the hot, melted butter is character- 
istic; the oleomargerine odor suggests meat. The taste, 
especially to those experienced, offers a valuable guide. 

Detection of Coloring Matter (Martin.) About 5 
grams of butter are extracted with Carbon Bisulphide 
containing 15% of Methyl or Ethyl Alcohol. The solu- 
tion separates into two layers, the lower containing the 
fat dissolved in the CSg, and the upper layer containing 



— 90 — 

the alcohol with the coloring matter, if present in solu- 
tion. 

This alcoholic layer may then be tested: Ammonia 
added burns the fluid brown : Turmeric. 

AgNOg produces a black color : Marigold. 

If the evaporated alcohol solution leaves a residue 
turning blue with H2SO4, Annato. 

Detection of Aniline Colors or Annatto (Doolittle.) 
Dissolve in two test tubes a small quantity of the but- 
ter (or fat), in ether. Add to one test tube 2c.c. HCl, 
to the other test tube 2c.c. KOH Solution. The anil- 
ine dye colors the acid tube red ; the annatto the KOH 
tube, after standing some time. 

Detection of Formaldehyde: Add the melted butter 
to milk, and test the milk for formaldehyde. (See 
Milk Analysis.) 

Detection of Salicylic Acid: 

Extract about 25 grams of butter with Sodium Bi- 
carbonate in water ; this will form Sodium Salicylate ; 
liberate the acid by H2SO4, and extract with ether; 
test the residue upon evaporation with Solution of Fer- 
ric Chloride: Violet color denotes Salicylic Acid. 

Edible Oils. 

The edible oils include Olive Oil, Cottonseed Oil, Se- 
same Oil, Rape Oil, and Peanut Oil. Adulteration of 
these oils consists chiefly of the addition of cheaper oils 
to the more expensive oils, thus Olive Oil may be adul- 
terated with Cottonseed Oil. The analysis is not always 
easy especially the quantitative estimation of adulter- 
ants. For the latter purpose the "saponification equiv- 



— 91 — 

alents" and "Iodine" and ''Bromine" values are of es- 
pecial value. For qualitative testing certain tests may 
be relied upon. The test for Cottonseed Oil will suffice 
for the present purpose. It is called : 

Halphen's Test. The reagent consists of equal parts 
of Amyl Alcohol and Carbon Bisulphide, containing 
1% of Sulphur in solution. Equal volumes of the fat 
and this reagent are mixed in a loosely-stoppered test 
tube, and the mixture is heated for 15 minutes in a bath 
of boiling brine: a red color denotes the presence of 
Cottonseed Oil. 



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